Smartwatches / Compare

Fitbit Versa 4 vs Xiaomi Watch S4

A

Product A: Fitbit

Versa 4

89 of 150 known

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B

Product B: Xiaomi

Watch S4

83 of 150 known

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Every value links to where we found it.

Only differences

AFitbit Versa 4

BXiaomi Watch S4

General

7 of 10 differ

Series

Versa3Press releaseblog.google/products-and-platforms/devices/fitbit/versa-4-sense-2Read 6 October 2026

Watch S3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q4 compares the Watch S4 with its predecessor, the Xiaomi Watch S3, in the same Watch S line.

Model numbersiMaker identifiers for this exact model and its listed variants. Excludes sibling models and other generations.

FB523, FB523BKBK-US, FB523SRAG-US, FB523RGRW-US, FB523RGRD1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Regulatory and Safety Notices: Model FB523 for FCC, IC, EU, UK and the IP rating. Retail colour SKUs are not stored.16Retailer pageabt.com/Fitbit-Versa-4-Graphite-Aluminum-Black-Strap-Fitness-Smartwatch-24mm-FB523BKBKUS/p/182318.htmlRead 7 October 2026Retail colour SKU FB523BKBK-US. Regulatory assembly remains FB523.17Retailer pageabt.com/Fitbit-Versa-4-Platinum-Aluminum-Waterfall-Blue-Strap-Fitness-Smartwatch-24mm-FB523SRAGUS/p/182320.htmlRead 7 October 2026Retail colour SKU FB523SRAG-US. Regulatory assembly remains FB523.18Retailer pageabt.com/Fitbit-Versa-4-Copper-Rose-Aluminum-Pink-Sand-Strap-Fitness-Smartwatch-24mm-FB523RGRWUS/p/182319.htmlRead 7 October 2026Retail colour SKU FB523RGRW-US. Regulatory assembly remains FB523.19Retailer pagephotopoint.ee/en/sports-watches/3626308-fitbit-versa-4-smart-watch-nfc-gps-satellite-amoled-touchscreen-heart-rate-monitor-activityRead 7 October 2026Retail colour SKU FB523RGRD. Regulatory assembly remains FB523.

M2425W1, BHR9195GL, BHR9197GL, BHR9199GL4Maker spec sheet (PDF)i02.appmifile.com/229_operatorx_operatorx_xm/29/08/2026/0506b1d933bea38854867532d7b1e253.pdfRead 15 October 2026EU Declaration of Conformity for radio equipment model M2425W1, Smart Watch, listed on Xiaomi's declaration page as Xiaomi Watch S4. The 41 mm Watch S4 is M2502W1 and is a separate product. The standards list covers Bluetooth, NFC and GNSS and has no cellular standard.6Maker product pagemi.com/global/service/support/declaration.htmlRead 15 October 2026Declaration page lists Xiaomi Watch S4 M2425W1 with EU DoC and PSTI documents, separate from Watch S4 41mm M2502W1.7Spec databasegsmarena.com/xiaomi_watch_s4-13476.phpRead 15 October 2026Spec page lists models M2424W1 and M2425W1. Only M2425W1 is documented for the global model, so M2424W1 is not stored.11Retailer pageeuronics.ee/en/phones/watches/smart-watches/bhr9195gl/xiaomi-watch-s4-black-smart-watchRead 15 October 2026Retailer product code BHR9195GL for the black Xiaomi Watch S4, 44.5 g, 486 mAh, Bluetooth 5.3, 4G No.13Retailer pagepood.datafox.ee/xiaomi-watch-s4-rainbow-smart-watchRead 15 October 2026Rainbow product code BHR9199GL.14Retailer pageachatmoinscher.com/comparateur-de-prix-Montre-connectee-sportive/montre-intelligente-xiaomi-s4-bhr9197gl-gris-argente-6941812707432.htmlRead 15 October 2026Silver product code BHR9197GL.

GTIN / EAN

810073611450, 810073611474, 810073611481, 81003885874616Retailer pageabt.com/Fitbit-Versa-4-Graphite-Aluminum-Black-Strap-Fitness-Smartwatch-24mm-FB523BKBKUS/p/182318.htmlRead 7 October 2026Exact FB523BKBK-US Black / Graphite Aluminum listing identifies 810073611450. Regional identifiers are not exchanged.17Retailer pageabt.com/Fitbit-Versa-4-Platinum-Aluminum-Waterfall-Blue-Strap-Fitness-Smartwatch-24mm-FB523SRAGUS/p/182320.htmlRead 7 October 2026Exact FB523SRAG-US Waterfall Blue / Platinum Aluminum listing identifies 810073611474. Regional identifiers are not exchanged.18Retailer pageabt.com/Fitbit-Versa-4-Copper-Rose-Aluminum-Pink-Sand-Strap-Fitness-Smartwatch-24mm-FB523RGRWUS/p/182319.htmlRead 7 October 2026Exact FB523RGRW-US Pink Sand / Copper Rose Aluminum listing identifies 810073611481. Regional identifiers are not exchanged.19Retailer pagephotopoint.ee/en/sports-watches/3626308-fitbit-versa-4-smart-watch-nfc-gps-satellite-amoled-touchscreen-heart-rate-monitor-activityRead 7 October 2026Exact FB523RGRD Beet Juice / Copper Rose Aluminum listing identifies 810038858746. Regional identifiers are not exchanged.

6941812732403, 6941812707432, 694181271166812Retailer pagepood.datafox.ee/xiaomi-s4-smartwatch-blackRead 15 October 2026Black BHR9195GL, EAN 6941812732403.13Retailer pagepood.datafox.ee/xiaomi-watch-s4-rainbow-smart-watchRead 15 October 2026Rainbow BHR9199GL, EAN 6941812711668.14Retailer pageachatmoinscher.com/comparateur-de-prix-Montre-connectee-sportive/montre-intelligente-xiaomi-s4-bhr9197gl-gris-argente-6941812707432.htmlRead 15 October 2026Silver BHR9197GL, EAN 6941812707432.

AnnouncediThe maker's first announcement of this model. This is separate from first retail availability.

24 August 20223Press releaseblog.google/products-and-platforms/devices/fitbit/versa-4-sense-2Read 6 October 2026Fitbit blog post dated Aug 24, 2022. Pre-orders started that day with worldwide availability this fall.

29 October 20247Spec databasegsmarena.com/xiaomi_watch_s4-13476.phpRead 15 October 2026Spec page: announced and released 29 October 2024 in China. The global model followed in March 2025.

Status

Available2Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026Google Store sells Versa 4 at 199.95 USD on the access date. That is a current price, not the launch price.

Available2Maker product pagemi.com/global/product/xiaomi-watch-s4Read 15 October 2026The global product page is live with specs and a buy link. GSMArena lists it as available.

PredecessoriThe model this one directly replaced, in the same line, tier and size, as the maker or a trusted review names it.

Not available

Not available

SuccessoriThe model that directly replaced this one, in the same line, tier and size. A revision such as a Slim or OLED model does not count when a next generation exists.

Not available

Xiaomi Watch S5 46mm15Reviewgsmarena.com/xiaomi_unveils_smart_band_10_pro_buds_6_sound_play_speaker-news-73032.phpRead 23 October 2026GSMArena says the Xiaomi Watch S5 comes as the successor to the Watch S4.

Launch price (US)iThe maker's US launch MSRP for the stated configuration, excluding tax. Current store prices and later discounts do not qualify.

$229.954Press releaseblog.google/products-and-platforms/devices/fitbit/fitbit-sense-2-versa-4Read 6 October 2026Versa 4 is now available for $229.95 (USD). The Aug 24, 2022 announcement gives the same price. No euro launch price was found in a maker source.

Not available

Launch price (EU)iThe maker's euro launch price for the stated configuration, including VAT as published. Current store prices and later discounts do not qualify.

Not available

€159.9910Press articlefonearena.com/blog/447624/xiaomi-buds-5-pro-watch-s4-electric-scooter-5-max-price-global.htmlRead 15 October 2026Price 159.99 euros for the Watch S4. The article lists no colours and gives no tax treatment. Retail listings put the Rainbow edition at 169.99 euros, which is not a launch price and is not stored.

MarketsiISO country or region codes where this exact model or variant is sold. A source page's language does not establish availability.

US, GB, DE, EE2Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026US, GB and DE maker stores offer the model. EE is a documented archived Beet retail listing, not a current-stock assertion.10Maker product pagestore.google.com/gb/product/fitbit_versa_4_specsRead 7 October 2026GB store offers Versa 4 at GBP 179.99 with Buy and all four colours. Current price is not a launch price.11Maker product pagestore.google.com/de/product/fitbit_versa_4_specsRead 7 October 2026DE store offers Versa 4 at EUR 199.95 with Kaufen and all four colours. Current price is not a launch price.19Retailer pagephotopoint.ee/en/sports-watches/3626308-fitbit-versa-4-smart-watch-nfc-gps-satellite-amoled-touchscreen-heart-rate-monitor-activityRead 7 October 2026Exact Beet FB523RGRD SKU was listed by Estonian retailer with Estonia delivery. Listing is now archived. This documents historical market scope rather than current stock.

EU10Press articlefonearena.com/blog/447624/xiaomi-buds-5-pro-watch-s4-electric-scooter-5-max-price-global.htmlRead 15 October 2026Euro price from European announcement coverage. The global launch was at MWC 2025.

ColoursiThe maker's own colour names

Black / Graphite Aluminum, Waterfall Blue / Platinum Aluminum, Pink Sand / Copper Rose Aluminum, Beet Juice / Copper Rose Aluminum2Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026

Black, Silver, Rainbow1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Silver, Rainbow and Black.

Segment

Smartwatch2Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026Page title: Fitbit Versa 4 Smartwatch. The Aug 24, 2022 Fitbit blog calls it a fitness smartwatch.

Smartwatch2Maker product pagemi.com/global/product/xiaomi-watch-s4Read 15 October 2026The page sits under Wearables as the Xiaomi Watch S4 smartwatch with a rotating crown and 150+ sports modes.

OS updates promisediYears of explicitly promised OS updates. A security-only support period does not establish an OS-upgrade promise.

Not available

Not available

Security updates untiliExact end date published for security-update support of this model. Do not calculate it from a stated number of years. A security-only period does not promise OS upgrades.

Not available

2 March 20275Maker spec sheet (PDF)i02.appmifile.com/791_operatorx_operatorx_xm/05/03/2026/e12c7be544083cc45f26f933fa49ae28.pdfRead 15 October 2026UK PSTI statement for M2425W1 dated 2025/2/6: the defined support period is until 3/2/2027. Xiaomi's other PSTI statements use month/day/year, such as 11/15/2026 and 2/27/2028, so this reads as 2 March 2027. This is a security-support period, not an OS-upgrade promise.

Case

6 of 8 differ

Case sizeiMarketed case-size options. The marketed size can differ from physical case height, such as ceramic editions. Base dimensions describe the smallest base-material case.

Not available

47.3mm1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026The maker states 47.3 mm x 47.3 mm x 12.0 mm. The separate 41 mm Watch S4 has its own page and is not included.

Case shape

Rectangular7Reviewtechradar.com/reviews/fitbit-versa-4Read 6 October 2026Design and display: a friendly-looking square-faced watch. The Google Store gives equal 40.5 mm length and width.

Round3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q2: round AMOLED display and 47.3 mm diameter.

Case materialiMaterial of the housing body, not just the bezel. Use Mixed when the maker describes a mixture of housing/frame materials. Read the published-material field for the parts and proportions.

Aluminium1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Materials: The housing and buckle on Versa 4 are made of aluminum.

Aluminium1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Aluminum alloy frame. The bezel is stainless steel according to the support FAQ.3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q2: middle frame entirely aluminium alloy, bezel stainless steel.

Case material (as published)

Aluminum1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026

Aluminium alloy middle frame with PVD coating and stainless steel bezel3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q2 and the S3 comparison: aluminium alloy with PVD coating, stainless steel bezel.

BackiMaterial of the back of the smallest base-material case. Other materials or regional editions can differ. See source notes.

Plastic7Reviewtechradar.com/reviews/fitbit-versa-4Read 6 October 2026Design and display: the bezel is aluminum and the rear is plastic. Fitbit publishes no back material.

Not available

Case dimensionsiPhysical case height, width and thickness. The source note states exclusions such as the heart-rate sensor protrusion.

Height40.5Width40.5Thickness11.2mm(1.6 × 1.6 × 0.4 in)2Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026Dimensions and weight: Length 40.5 mm, Width 40.5 mm, Height 11.2 mm. Height is stored as thickness. The listed weight of 37.64 g does not say whether it includes the band, so neither weight field is filled.

Height47.3Width47.3Thickness12mm(1.9 × 1.9 × 0.5 in)1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 202647.3 x 47.3 x 12.0 mm. The maker excludes the strap and protrusions. The FAQ gives 14.13 mm thickness with the heart rate bump.3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q2: diameter 47.3 mm, thickness 12 mm excluding the deco and heart rate sensor.

Weight (case only)iWatch body without a strap. An unqualified published weight must not be assumed to exclude the strap.

Not available

44.5g(1.6 oz)1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 202644.5 g approx., without the in-box strap.3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q2: 44.5 +/- 1 g, excluding the strap.

Weight with strapiWatch with the stated strap attached. Strap material and case size belong in the source note. Reviewer measurements belong in measured fields.

Not available

Not available

Durability

2 of 8 differ

Water resistanceiStatic water-pressure rating in atmospheres. It is not a safe swimming or diving depth. Diving limits are listed separately.

5ATM1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Environmental conditions: Water resistant up to 50 meters. Fitbit publishes no ATM figure. 50 m equals the 5 ATM static pressure rating.12Maker product pagestore.google.com/gb/magazine/google_pixel_watch_compareRead 7 October 2026Maker comparison explicitly publishes 5 ATM for Versa 4. The existing value is now directly maker-supported, without deriving pressure from metres.

5ATM1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 20265 ATM, described as 50 m static pressure. The maker says it is not suitable for hot showers, saunas or diving.3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q9: 5 ATM, equivalent to 50 m, for pool and shallow-water use and not for diving.

Water resistance standard

IEC 605291Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Manual printed page 74 explicitly rates FB523 IPX8 under IEC 60529 up to 50 metres. IEC 60529 applies to water ingress, not an inferred ISO pressure or diving test. Maker comparison independently publishes 5 ATM.

Not available

Dust and water rating

IP6X, IPX81Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026IP Rating section: IPX8 under IEC 60529 up to a depth of 50 meters, and IP6X dust-tight. Stored as the two published codes.

Not available

Dive rating

Not available

Not available

Max dive depthiMaker-rated depth for the stated diving use, not a conversion from the water-resistance pressure rating.

Not available

Not available

MIL-STD-810iMaker claim that the watch was tested against specified MIL-STD-810 methods. It is not a guarantee for every military-standard test.

Not available

Not available

MIL-STD-810 tests

Not available

Not available

Operating temperatureiPublished operating range. Source notes identify on-wrist limits and other operating conditions. Storage or charging limits are excluded.

Min-10Max45°C1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Environmental conditions table: operating temperature 14 to 113 F (-10 to 45 C). Non-operating and charging (0 to 35 C) ranges excluded. The Google Store specs page prints -14 to 113 F, which conflicts. The manual table, which states both units, is used.

Min-10Max45°C9Retailer pageteamplush.by/enRead 15 October 2026Same reseller copy of the manual: working temperature -10 to 45 C.

Display

7 of 14 differ

Display type

OLED2Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026

OLED1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Spec row: 1.43-inch AMOLED display. No LTPO is stated.

Display type (as published)

AMOLED2Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026Display: AMOLED display, Corning Gorilla Glass 3.

AMOLED1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Spec row: AMOLED display.

Screen sizeiPublished active display diagonal for a rectangular display, or diameter for a round display. Do not calculate it from pixels or display area.

1.58in(4 cm)6Reviewpcmag.com/reviews/fitbit-versa-4Read 6 October 2026Both feature a 1.58-inch AMOLED display (Versa 4 and Sense 2). Fitbit publishes no diagonal. Android Central, Trusted Reviews and Stuff state the same 1.58 inches.

1.43in(3.6 cm)1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 20261.43-inch AMOLED display, 466 x 466 pixels.

Resolution

336 × 336px6Reviewpcmag.com/reviews/fitbit-versa-4Read 6 October 2026The 336-by-336-pixel display. TechRadar and Android Central state 336 x 336 as well. No pixel density is stored because none is published.7Reviewtechradar.com/reviews/fitbit-versa-4Read 6 October 2026The screen is a 336 x 336 pixel OLED just like the Versa 3's.

466 × 466px1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026

Pixel densityiPublished pixel density. A rectangular diagonal formula must not be applied to a round display.

Not available

326ppi1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Published PPI 326.

Display area

Not available

Not available

Touchscreen

Yes1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Navigate Versa 4: Versa 4 has a color AMOLED touchscreen display and 1 button.

Yes1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026

Max refresh rateiHighest published display refresh rate in active operation.

Not available

60Hz1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 202660 Hz refresh rate. The maker notes it may vary across interfaces.

Min refresh rateiLowest published display refresh rate, usually in always-on mode. It is not the active-use minimum unless stated.

Not available

Not available

Peak brightnessiMaker peak-brightness claim. It may apply to a small area or bright ambient light. Full-screen limits and battery/temperature conditions belong in source notes.

Not available

2,200nits1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Peak 2200 nits is when only part of the screen lights up. HBM 1500 nits is the full-screen maximum. No reviewer measurement is substituted.

Minimum brightness

Not available

Not available

Always-on display

Yes1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Adjust always-on display section.

Yes2Maker product pagemi.com/global/product/xiaomi-watch-s4Read 15 October 2026Support FAQ has the AOD controls. The overview page announces colour always-on displays.3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q26: Always-on display supported, with Smart or Scheduled modes.

Display cover

Gorilla Glass2Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026

Other glass3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q2: Panda Glass cover. It is not a named Gorilla Glass or sapphire.

Display cover (as published)

Corning Gorilla Glass 32Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026

Panda Glass3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q2: Panda Glass.

Platform

6 of 15 differ

Platform

Proprietary3Press releaseblog.google/products-and-platforms/devices/fitbit/versa-4-sense-2Read 6 October 2026

Proprietary1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Operating system: Xiaomi HyperOS 2, Xiaomi's own software. No Wear OS or other third-party watch platform is named.

OS at launch

Fitbit OS3Press releaseblog.google/products-and-platforms/devices/fitbit/versa-4-sense-2Read 6 October 2026Powered by the new Fitbit OS. No version number is published.

Xiaomi HyperOS 21Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026

Software

Not available

Not available

Latest OS

Fitbit OS, firmware 220.3113Maker product pagesupport.google.com/googlehealth/answer/14236725Read 7 October 2026Latest maker-listed Versa 4 device firmware on access date. No unreported Fitbit OS major version is assigned. Updates are phased.

Not available

Works with

iOS, Android2Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026

Android, iOS1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Supports Android 8.0 and above, or iOS 14.0 and above.

Phone requirement

Google Health app on a compatible device running Apple iOS 16.4 or higher or Android OS 11.0 or higher2Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026Requirements section, current on the access date. The 2022 launch requirement may have been lower.

Android 8.0 or later, or iOS 14.0 or later, with the Mi Fitness app1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026The Mi Fitness app is required for pairing according to the support FAQ.

App store

No6Reviewpcmag.com/reviews/fitbit-versa-4Read 6 October 2026The Versa 4 does not support third-party app downloads, with the exception of watch faces.

Not available

Voice assistants

Amazon Alexa1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Voice Assistant: Amazon Alexa Built-in. Needs the phone app running in the background. Not available in all countries.

Not available

Chipset

Not available

Not available

Process

Not available

Not available

CPU cores

Not available

Not available

CPU configuration

Not available

Not available

Max CPU clock

Not available

Not available

GPU

Not available

Not available

Low-power coprocessor

Not available

Not available

Memory

None of 2 known

RAMiKeep published GB values as stated. Convert a source explicitly labelled MB using 1000 MB per GB and preserve its original figure and unit in the note. Do not assume MB means MiB. Convert explicit MiB or GiB to decimal GB through their byte definitions, recording the conversion in the note. This normalization does not establish an exact physical byte count.

Not available

Not available

StorageiTotal built-in storage the maker states, in decimal GB. Space available to the user is lower and goes in the source note. A figure the maker gives only as available space is not stored.

Not available

Not available

Health sensors

6 of 8 differ

Heart rate sensor

Multi-path optical heart rate sensor1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Sensors and Components: Multi-path optical heart rate tracker. Google Store spells it Multi-path optical heart rate sensor.

Heart rate sensor (with blood oxygen sensor)1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Sensors row: heart rate sensor (with blood oxygen sensor). No sensor generation is named.

ECG capabilityiElectrical heart sensing hardware with an ECG capability. The ECG app can require an eligible country, age and paired phone.

No4Press releaseblog.google/products-and-platforms/devices/fitbit/fitbit-sense-2-versa-4Read 6 October 2026The ECG app is named for Sense 2 only, while Irregular Heart Rhythm Notifications are on both watches. Versa 4 has no electrical heart sensor in its sensor list.6Reviewpcmag.com/reviews/fitbit-versa-4Read 6 October 2026The Sense 2 adds an electrocardiogram (ECG) sensor.

Not available

Blood oxygen sensingiBlood-oxygen sensing capability. App availability and medical status vary by market.

Yes1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Sensors and Components: red and infrared sensors for oxygen saturation (SpO2) monitoring. Not available in all countries and not for medical use.

Yes1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026

Skin temperature sensingiA sensor or supported function that measures skin temperature. It is not a core-body thermometer.

Yes1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Track your sleep and Advanced health metrics: skin temperature variation from personal baseline. It reports variation only, not an absolute temperature.2Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026Sensors and components: Device temperature sensor (skin temperature variation available in the Google Health app). Variation only, not in all markets.

Not available

Blood pressure featureiPublished blood-pressure feature category. Hypertension notifications are not numerical blood-pressure readings.

None14Spec databasegadgetsandwearables.com/technical-specs/fitbit-versa-4Read 7 October 2026Explicit absence of blood-pressure feature. Maker comparison also lacks blood-pressure trends.

Not available

Body composition sensor

Not available

Not available

Skin conductance (EDA)

No3Press releaseblog.google/products-and-platforms/devices/fitbit/versa-4-sense-2Read 6 October 2026The continuous EDA (cEDA) Body Response sensor is described for Sense 2 only. Versa 4 has no EDA sensor in its own sensor list.6Reviewpcmag.com/reviews/fitbit-versa-4Read 6 October 2026The Sense 2 adds a cEDA sensor and an ECG sensor that the Versa 4 lacks.

Not available

Medical clearancesiNamed regulatory clearances and their jurisdiction. General water resistance or an ECG sensor does not establish medical clearance.

Irregular Heart Rhythm Notifications: FDA clearance, Irregular Heart Rhythm Notifications: EU clearance4Press releaseblog.google/products-and-platforms/devices/fitbit/fitbit-sense-2-versa-4Read 6 October 2026Both of these tools have FDA and EU clearance: the Sense 2 ECG app and the Irregular Heart Rhythm Notifications on both watches. Select countries only, not for people under 22 or with known AFib.

Not available

Motion and environment sensors

2 of 9 differ

Accelerometer

Yes1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026

Yes1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026

Accelerometer range

Not available

Not available

Gyroscope

No12Maker product pagestore.google.com/gb/magazine/google_pixel_watch_compareRead 7 October 2026Versa 4 column explicitly lacks the gyroscope.

Yes1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026

Barometric altimeter

Yes1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Sensors and Components: Altimeter, which tracks altitude changes. Restart section names a small hole on the device for the altimeter, which is the pressure-sensor vent. Published only as Altimeter.

Yes1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026

Compass

No12Maker product pagestore.google.com/gb/magazine/google_pixel_watch_compareRead 7 October 2026Versa 4 column explicitly lacks the compass.

Yes1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Sensors row lists an electronic compass.

Ambient light sensor

Yes1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026

Yes1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 20263Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Brightness Auto adjusts to ambient light.

Depth gauge

Not available

Not available

Depth gauge rangeiPublished measurement range of the depth gauge, distinct from maximum diving depth and water-pressure resistance.

Not available

Not available

Water temperature sensor

Not available

Not available

Health and fitness

2 of 5 differ

Health featuresiSupported health functions with country, phone and subscription restrictions in the source notes. Upcoming functions are not counted as available.

Continuous heart rate, Heart rate alerts, Irregular rhythm notifications, Blood oxygen app, Heart rate variability, Sleep tracking, Sleep stages, Stress tracking, Readiness score, Cycle tracking1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Today app stats: heart rate, oxygen saturation, readiness, stress management score, menstrual health. Track your sleep: sleep stages. Receive heart-rate notifications: high and low heart rate. Advanced health metrics: heart-rate variability. Daily readiness and some detail need Fitbit Premium per the maker blog.3Press releaseblog.google/products-and-platforms/devices/fitbit/versa-4-sense-2Read 6 October 202624/7 heart rate monitoring, sleep tracking and Stress Management Score.4Press releaseblog.google/products-and-platforms/devices/fitbit/fitbit-sense-2-versa-4Read 6 October 2026Irregular Heart Rhythm Notifications on both watches.

Continuous heart rate, Blood oxygen app, Sleep tracking, Sleep stages, Stress tracking, Cycle tracking2Maker product pagemi.com/global/product/xiaomi-watch-s4Read 15 October 2026Overview: heart rate, stress, blood oxygen and sleep monitoring, all-day options that need to be switched on. These are not medical features.3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Health pages: all-day heart rate, blood oxygen and stress, sleep stages (deep, light, REM, awake) and the Cycles app.

Fitness featuresiSupported workout functions. A sport-profile name alone does not prove advanced metrics such as running power or running dynamics. Trackback follows the recorded route back to the start. A compass arrow that points straight to the start does not count.

Automatic workout detection, VO2 max, Pool swim, Interval workouts, Turn-by-turn navigation1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Track your exercise automatically (SmartTrack, 15 minute minimum). Exercise settings list Pool Length and Interval. Google Maps app gives turn-by-turn directions and needs the paired phone nearby with the app running. View your cardio fitness score in the Fitbit app (stored as vo2_max, see the Google Health VO2 max help page).9Maker product pagesupport.google.com/googlehealth/answer/14237924Read 6 October 2026Learn about your VO2 max: tap VO2 max (formerly known as cardio fitness score). The Versa 4 manual names the cardio fitness score. VO2 max is estimated during outdoor runs with GPS.

Automatic workout detection, VO2 max, Training load, Running dynamics, Pool swim, Open water swim2Maker product pagemi.com/global/product/xiaomi-watch-s4Read 15 October 2026Overview: running form recognition (vertical ratio, vertical amplitude, ground contact time) and 150+ sports modes.3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Workout Q1: auto detect for walking, running, cycling, rower, elliptical and jump rope. Q2 workout data: vertical stride ratio, vertical amplitude and ground contact time in running. 17 modes give pro data including pool and open water swimming. The Training State app manages training load.11Retailer pageeuronics.ee/en/phones/watches/smart-watches/bhr9195gl/xiaomi-watch-s4-black-smart-watchRead 15 October 2026Retailer spec tab lists maximal oxygen uptake (VO2 max) measurements as Yes.

Sport profilesiPublished count of distinct sport/activity profiles. A claim such as 180+ is not an exact integer count.

Not available

Not available

Dive modesiActual supported dive modes. Water resistance or a depth app alone does not establish decompression-capable scuba support.

Not available

Not available

External sensorsiTypes of external workout sensors the watch can pair with. GPS reception, phone data and built-in sensors do not qualify.

Not available

Not available

Safety

4 of 6 differ

Fall detectioniAutomatic fall detection. Incident detection restricted to recorded workouts is not counted as general fall detection.

No12Maker product pagestore.google.com/gb/magazine/google_pixel_watch_compareRead 7 October 2026Versa 4 column explicitly lacks general fall detection.

Not available

Car crash detection

No12Maker product pagestore.google.com/gb/magazine/google_pixel_watch_compareRead 7 October 2026Versa 4 column explicitly lacks car crash detection.

Not available

Emergency SOSiA manual emergency alert to emergency services or preset contacts. Source notes identify the recipient, paired-phone requirement and country limits. Satellite is listed separately.

No12Maker product pagestore.google.com/gb/magazine/google_pixel_watch_compareRead 7 October 2026Versa 4 column explicitly lacks manual emergency SOS.

Not available

Emergency sireniPublished or measured siren sound level in decibels. Audible distance alone does not establish this value. Measurement distance belongs in source notes.

Not available

Not available

Live location sharingiShares live location during supported use. A paired phone or data subscription may be required.

Not available

Not available

Dedicated LED flashlightiA dedicated hardware LED flashlight. Lighting the display white is not counted.

No14Spec databasegadgetsandwearables.com/technical-specs/fitbit-versa-4Read 7 October 2026Explicit absence of dedicated LED flashlight. Display illumination is not that hardware feature.

Not available

Positioning

3 of 3 differ

PositioningiPublished satellite systems and signal bands. Do not infer bands from dual-frequency support alone.

GPS, GLONASS1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Sensors and Components: Built-in GPS receiver + GLONASS. Dynamic GPS can use the phone's GPS instead to save battery. No band or dual-frequency claim.

GPS (L1 + L5), Galileo (E1 + E5a), GLONASS (G1), BeiDou (B1I + B1C + B2a), QZSS (L1 + L5)1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Satellite systems: GPS, Galileo, Glonass, BeiDou and QZSS. The overview page says L1+L5 dual-frequency GNSS. The per-constellation bands come from the reseller copy of the manual regulatory table.7Spec databasegsmarena.com/xiaomi_watch_s4-13476.phpRead 15 October 2026Positioning: GPS (L1+L5), GLONASS, GALILEO, BDS, QZSS.9Retailer pageteamplush.by/enRead 15 October 2026Reseller page reproducing the M2425W1 manual regulatory table: GPS L1 / Galileo E1 / GLONASS G1 / BDS B1I, B1C / QZSS L1 at 1559-1610 MHz, and GPS L5 / Galileo E5a / BDS B2A / QZSS L5 at 1164-1215 MHz. This agrees with the maker's L1+L5 claim and GSMArena. Xiaomi's own manual PDF was not found, so the reseller copy is the source.

Dual-band GNSSiMaker-stated dual-frequency satellite reception. Supported constellations and signal bands are listed separately.

Not available

Yes2Maker product pagemi.com/global/product/xiaomi-watch-s4Read 15 October 2026Overview: L1+L5 dual-frequency GNSS of five satellite positioning systems from an independent chip.

Offline mapsiMap data stored on the watch and usable without live phone data. GPX routes or breadcrumb tracks alone are not offline maps.

No14Spec databasegadgetsandwearables.com/technical-specs/fitbit-versa-4Read 7 October 2026Explicit no offline maps. Maker manual requires phone navigation and background app. Directions are not stored cartographic maps.

Not available

Connectivity

6 of 15 differ

BluetoothiPublished Bluetooth support for this model. The version is recorded separately. Unknown version does not mean the radio is absent.

Not available

Yes1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026

Bluetooth version

5.01Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Wireless technology: Bluetooth 5.0 radio transceiver and NFC chip. Wi-Fi hardware is listed as deactivated and cannot be turned on, so no Wi-Fi standard is stored.

5.31Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Wireless connectivity: Bluetooth 5.3.7Spec databasegsmarena.com/xiaomi_watch_s4-13476.phpRead 15 October 2026Bluetooth 5.3, A2DP, LE.9Retailer pageteamplush.by/enRead 15 October 2026The copied table lists Bluetooth 5.3 at 2400-2483.5 MHz.

Wi-FiiPublished Wi-Fi support for this model. The standard and bands are recorded separately. Unknown standard does not mean Wi-Fi is absent.

Not available

No7Spec databasegsmarena.com/xiaomi_watch_s4-13476.phpRead 15 October 2026WLAN: No.9Retailer pageteamplush.by/enRead 15 October 2026The copied radio table lists only GNSS, Bluetooth and NFC, with no Wi-Fi radio.

Wi-Fi standard

Not available

Not available

Wi-Fi bands

Not available

Not available

CellulariTrue when a cellular edition is sold. A variant row states whether that individual model has cellular hardware.

No8Reviewtomsguide.com/reviews/fitbit-versa-4Read 7 October 2026Fitbit's watches don't have cellular support. Only one radio configuration (FB523, Bluetooth and NFC) exists in the manual.

No7Spec databasegsmarena.com/xiaomi_watch_s4-13476.phpRead 15 October 2026Versions: eSIM and NFC (China), Bluetooth and NFC (China), Bluetooth only (International). The global page and the EU declaration list no cellular radio, so the global model has no cellular.

Network

Not available

Not available

4G bandsiPublished LTE bands for the stated regional cellular model. Do not transfer bands to another region or Wi-Fi-only model.

Not available

Not available

5G bandsiPublished 5G NR bands for the stated regional cellular model. RedCap support does not establish conventional full-bandwidth phone 5G.

Not available

Not available

NFCiSome regions sell an NFC edition, so it is per variant.

Yes1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026

Yes1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026NFC: Supported. The maker says availability may vary by region.9Retailer pageteamplush.by/enRead 15 October 2026The copied regulatory table lists an NFC operating frequency of 13.56 MHz.

Contactless payments

Yes1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026

Yes2Maker product pagemi.com/global/product/xiaomi-watch-s4Read 15 October 2026NFC payment supports Mastercard and Visa terminals. Availability varies by region and issuing bank.

Payment services

Google Wallet1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Contactless Payments: set up Google Wallet in the app. The manual also names the legacy Fitbit Pay app, which Google is phasing out. Card, bank and country limits apply.

Xiaomi Pay3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026NFC related: bank cards are added through Mi Fitness, Device, Apps, Xiaomi Pay.

Ultra-wideband

No12Maker product pagestore.google.com/gb/magazine/google_pixel_watch_compareRead 7 October 2026Versa 4 column explicitly lacks UWB radio.

Not available

Satellite

None12Maker product pagestore.google.com/gb/magazine/google_pixel_watch_compareRead 7 October 2026No satellite SOS. Published transmitters are Bluetooth/NFC. GPS reception is separate.

Not available

ANT+

Not available

Not available

Audio

2 of 4 differ

Speaker

Yes1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Sensors and Components lists Speaker and Microphone. The Google Store rates the speaker at 75 dB SPL at 10 cm. That is not an emergency siren.

Yes1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026

Microphones

Not available

21Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Spec row: 2 mics.

Calls on the watchiVoice-call capability of the marketed model, including sold cellular editions. Variant radio capability and paired-phone requirements still apply.

Phone only1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Answer or reject phone calls: on-wrist calls through the paired iPhone or Android phone, which must be nearby with the Fitbit app running. No cellular model exists.

Phone only1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Bluetooth calling: Supported while the watch stays connected to the phone's Bluetooth. Voice calls from third-party apps are not supported.

Music on the watchiPlays audio stored on the watch. Remote control of phone playback or streaming alone does not qualify.

No7Reviewtechradar.com/reviews/fitbit-versa-4Read 6 October 2026You can't store music on the watch. Tom's Guide also says you can't download music to the Versa 4.8Reviewtomsguide.com/reviews/fitbit-versa-4Read 7 October 2026You can't download music to the Versa 4 or install third-party apps.

Yes3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q28: local music playback on the watch. An Android phone downloads the music. An iPhone cannot download songs, but songs already on the watch play.

Controls

4 of 5 differ

ButtonsiPhysical controls used to operate the watch, excluding the rotating crown and strap-release buttons. A clickable rotating crown is counted only in Crown.

11Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Navigate Versa 4: color AMOLED touchscreen display and 1 button.

13Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q2: the 2 o'clock position has the function button and rotating crown. The 4 o'clock position has the power button. The crown is counted only in Crown.

Named operating buttonsiNames of operating buttons, excluding the crown and strap-release controls.

Button1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Maker calls the single operating control Button. Strap-release latches are excluded.

Power button (4 o'clock)3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q2: power button at 4 o'clock.

CrowniA crown that rotates to control the interface. A round push button that does not rotate is not a crown.

None1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026The controls are the touchscreen and 1 button. There is no rotating crown.

Rotating2Maker product pagemi.com/global/product/xiaomi-watch-s4Read 15 October 2026The overview describes a classic rotating crown.3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q2: stainless steel rotating crown that also works as a function button.

Rotating bezeliPhysical rotation or touch gestures around the display edge. A fixed decorative bezel is None.

Not available

None3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q11: the bezel is a removable decorative part that twists on for installation. The maker describes no bezel input.

Gestures

Turn your wrist, Briefly cover the watch face with your opposite hand, Triple-tap the screen1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Manual screen-wake setting documents selectable wrist-turn wake. Printed page 22 says briefly covering the face turns the screen off, except when always-on display is enabled. Printed page 20 says triple-tap zoom works after Magnify is enabled. These are interface gestures, not unsupported inertial sensor features.

Raise to wake, Double-tap to wake, Wrist flip, Wrist shake, Finger snap, Fist clench2Maker product pagemi.com/global/product/xiaomi-watch-s4Read 15 October 2026Quick gestures and a classic rotating crown are listed. The support FAQ names the gestures.3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q24 lists wrist flip, wrist shake, finger snap and fist. Fist works only with HyperOS 2 phones. Raise to wake and double-tap to wake are in the display settings.

Battery and charging

8 of 13 differ

Battery capacityiPublished battery capacity for the stated case size. Rated and typical capacity are distinguished in source notes.

Not available

486mAh1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Capacity 486 mAh. Rated or typical is not stated.

Claimed battery lifeiMaker endurance claims with distinct operating modes and case sizes. With solar describes augmentation of that estimate, not hardware capability. Use false for ordinary claims without solar augmentation, true for explicitly solar-aided claims, and omit it when solar qualification is unclear. Source notes state AOD, GNSS, music and solar conditions. Do not create a normal-use row from an AOD-only claim. Low power denotes the maker battery-saver mode. Keep its typical, light-use and always-on claims separate from standard-mode claims. GPS power saving identifies an intermediate reduced-accuracy GNSS saving preset. Source notes retain the maker's preset name and published conditions. Max battery GPS is the distinct maximum-saving claim. When the maker has only one GPS saving preset, it is GPS power saving.

AFitbit Versa 4

Mode	With solar	Hours (h)
Smartwatch	No	144
Always-on	No	72
GPS	No	12

Source5Maker product pagesupport.google.com/googlehealth/answer/14226518Read 6 October 2026Battery life table: Fitbit Versa 4* 6+ days, stored as 144 h as a minimum figure. Footnote *: always-on display and GPS need more frequent charging. If you turn on always-on display: Versa 4 up to 3 days (72 h). If you use built-in GPS continuously: Versa 4 up to 12 hours. The 2025 pre-production test footnote (**) belongs to Google Fitbit Air, not Versa 4.

BXiaomi Watch S4

Mode	With solar	Hours (h)
Smartwatch	No	360
Always-on	No	120

Source2Maker product pagemi.com/global/product/xiaomi-watch-s4Read 15 October 2026Up to 15 days typical usage, tested by Xiaomi Internal Labs with factory defaults, AOD off, 100 messages a day, 200 wrist raises a day, 90 minutes of GNSS sports a week and 10-minute heart rate checks. The FAQ gives 14.5 days with an iPhone and 5 days with the Smart AOD option on. Days are converted exactly to hours.3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Charging and Battery Q1: typical 15 days (14.5 with an iPhone) and AOD 5 days, with the stated test conditions.

Smartwatch mode (claimed)iMaker normal-use smartwatch claim without solar. A watch with only an explicit AOD-mode claim has no value here. Workloads differ and source notes must be read.

144h=CalculatedFrom Claimed battery life

360h=CalculatedFrom Claimed battery life

AOD battery life (up to)iMaker claimed smartwatch endurance with the always-on display enabled and without solar, for the base case. Source notes preserve workload and case conditions. This is a claim, not a measured test or an AOD-off estimate.

72h=CalculatedFrom Claimed battery life

120h=CalculatedFrom Claimed battery life

GPS mode (claimed)iMaker regular GPS/GNSS activity claim without solar, for the base case. AOD, multi-band, music and power-saving conditions have separate rows when published.

12h=CalculatedFrom Claimed battery life

Not available

Solar chargingiPublished solar charging hardware capability. An ordinary battery estimate without solar augmentation does not prove that the watch lacks solar charging hardware.

Not available

Not available

Charging methodiThe connection at the watch, not the cable end at the USB adapter. A proprietary inductive puck is not Qi unless interoperability is explicitly established.

Magnetic pins1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Charge your watch: the cable end attaches magnetically to the port on the back and its pins align with the port.

Magnetic pins1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Charging port: 2-pin magnetic charging dock.

Charging guidanceiPublished charging requirements, nominal estimates and compatibility guidance. Keep adapter ratings separate from power accepted by the watch.

Not available

2-pin magnetic charging dock with a USB-A cable. The FAQ asks for a USB-A charger with 5 V output and at least 0.5 A.1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026The support FAQ gives the supply requirement.3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Charging Q2: USB-A charger with 5 V and at least 0.5 A output.

Max charging power (watch)iPublished maximum charging power at the watch. Adapter rating or charger input power does not prove the power accepted by the watch.

Not available

Not available

Fast chargingiAn explicit fast-charging capability claim. A short charging time or high adapter wattage alone does not qualify.

Yes4Press releaseblog.google/products-and-platforms/devices/fitbit/fitbit-sense-2-versa-4Read 6 October 2026Fast charging gets you a full day's worth of battery in just 12 minutes.

Yes2Maker product pagemi.com/global/product/xiaomi-watch-s4Read 15 October 2026Overview headline: 5 minutes of fast charging delivers 2 days of usage.

Quick charge claimiMaker claim for usage from a short charge. Source notes identify the usage workload, such as normal use or sleep tracking.

Charge time12 minUse time24 h1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Charge Versa 4 for 12 minutes for 24 hours of battery life.

Charge time5 minUse time48 h2Maker product pagemi.com/global/product/xiaomi-watch-s4Read 15 October 20265 minutes of charging for 2 days of usage. The FAQ says this follows the typical battery model, which is the typical-use workload.3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Charging Q1: 5 minutes of charging provides a 2-day boost under the typical battery model.

Charge 0 to 80% (claimed)iMaker claim for charging an empty battery to 80%. Charger and approximate qualifiers belong in source notes.

Not available

Not available

Full charge time (claimed)iMaker advertised nominal full-charge duration. Approximate or theoretical maker estimates are allowed, with their conditions in source notes. Partial-charge intervals do not qualify. Measured 0 to 100% tests have a separate field.

120min2Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026Battery and power: Charge time (0-100%): Two hours. The manual says charging fully takes about 1-2 hours.

60min3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Charging Q1 and Q2: about 60 minutes to fully charge.

Measured

2 of 4 differ

Peak brightness (measured)iReviewer measurement. Source notes state screen area, mode and ambient light. A small-area peak claim cannot be replaced with a full-screen measurement.

Not available

Not available

Battery life (measured)iReviewer-observed mixed-use endurance. Source notes state case size, AOD, workout use and whether it was a complete discharge. Extrapolation from partial discharge is excluded.

Not available

Not available

Battery tests (measured)iReviewer-observed endurance, with case size and test settings in source notes. Partial-discharge projections are not stored as measured endurance.

AFitbit Versa 4

Not available

BXiaomi Watch S4

Test	Hours (h)
Mixed use, always-on	48

Source8Reviewgsmarena.com/xiaomi_watch_s4_review-news-67715.phpRead 15 October 2026Reviewer used AOD, notifications, a one-hour daily workout and sleep tracking. The most was three days when the watch nearly died, and two days was a consistent result. Stored as about 48 hours. Firmware and display brightness are not stated.

Full charge time (measured)iReviewer measurement from empty to full, not 0-80% or a charge from 5%. Source notes name the charger and case size.

60min8Reviewtomsguide.com/reviews/fitbit-versa-4Read 7 October 2026Reviewer observed depleted-to-full charging using the proprietary USB-A-ended charging arrangement. Standard 40.5 mm Copper Rose review unit. USB power adapter, ambient temperature and firmware are unstated. This is a measured result, separate from the maker two-hour claim. Partial-discharge runtime projections are not added.

Not available

Strap

5 of 6 differ

Lug widthiDistance between standard strap attachment lugs, not the decorative width of a proprietary strap. Unknown for custom connectors unless the maker publishes lug width.

Not available

22mm3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q7: strap width 22 mm.

Quick-release strapiThe supplied strap can be detached through its quick-release mechanism. Compatibility with quick-release replacement straps alone does not qualify.

Yes1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Change the band: slide the flat latch button toward the band and pull. Attach by pressing until it clicks. No tools.

Yes3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q6: the watch supports quick-release straps released through the spring bar.

Strap systemiPublished attachment system and compatible case sizes. Proprietary connectors are distinguished from standard spring bars.

Proprietary latch connector. Fitbit Sense, Sense 2 and Versa 3 bands are compatible.1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Change the band: Fitbit Sense, Fitbit Sense 2, and Fitbit Versa 3 bands are compatible with Versa 4. Turn over Versa 4 and find the band latches. Slide the flat button toward the band to release the latch. Proprietary connector, no lug width published.

22 mm quick-release straps with spring bars3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Q6 and Q7: quick-release spring-bar straps, any 22 mm strap.

Strap materialiMaterial of the supplied strap for the stated package. Do not substitute material from another band sold separately.

Other1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Supplied classic band is elastomer. Other preserves that wording without guessing silicone, HNBR or fluoroelastomer.

Fluoroelastomer3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Spec page names fluororubber straps for Black and Silver. Fluororubber is stored as fluoroelastomer.

Strap

Classic band2Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026Maker box lists Classic band in small and large sizes. Manual printed page 57 states flexible durable elastomer. band_material=other preserves that published material without guessing a specific polymer.

Fluororubber strap3Maker product pagemi.com/global/support/faq/details/KA-517264Read 15 October 2026Spec page strap rows for Black and Silver.

Strap sizesiPublished wrist-circumference range for the stated strap or case. Source notes distinguish an overall compatible wrist range from one supplied strap size.

AFitbit Versa 4

Size	Wrist (min) (mm)	Wrist (max) (mm)
Small	140	180
Large	180	220

Source1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Band size table: Small 140-180 mm, Large 180-220 mm wrist circumference. The Google Store specs page prints Small 5.1-7 in and Large 6.5-8.6 in. The manual table is used.

BXiaomi Watch S4

Size	Wrist (min) (mm)	Wrist (max) (mm)
Black fluororubber strap	140	210

Source1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026The Black and Silver fluororubber straps have an adjustable length of 140-210 mm approx. The maker publishes strap length, stored as the wrist range. The Rainbow set with fluororubber and nylon straps is 135-210 mm.

Regulatory

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FCC ID

XRAFB5231Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026USA FCC statement: Model FB523, FCC ID XRAFB523. IC 8542A-FB523.

Not available

SAR limb (US)iPublished limb/wrist SAR for the stated base regional model under the US regime. Other case sizes or radio versions can differ. Head or body SAR is excluded.

Not available

Not available

SAR limb (EU)iPublished limb/wrist SAR for the stated base regional model under the EU regime. Other case sizes or radio versions can differ. Head or body SAR is excluded.

Not available

0.232W/kg9Retailer pageteamplush.by/enRead 15 October 2026Same reseller copy: maximum SAR on the wrist 0.232 W/kg with no gap, against a 4.0 W/kg wrist limit averaged over 10 g, under the EU declaration. The near-mouth value of 0.132 W/kg is a body value and is not stored.

Other certifications

RED (2014/53/EU), UK Radio Equipment Regulations 2017, IEC 62368-1:20181Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Manual printed page 62 declares FB523 compliance with RED 2014/53/EU. Printed page 72 declares UK Radio Equipment Regulations 2017. Printed page 74 lists testing to IEC 62368-1:2018 safety certification. These are model declarations and safety tests, not medical, military or diving certifications.

EU RED 2014/53/EU conformity, RoHS 2011/65/EU conformity4Maker spec sheet (PDF)i02.appmifile.com/229_operatorx_operatorx_xm/29/08/2026/0506b1d933bea38854867532d7b1e253.pdfRead 15 October 2026The declaration covers RE Directive 2014/53/EU and RoHS Directive 2011/65/EU.

In the box

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In the box

Fitbit Versa 4, Classic band (small & large), Charging cable2Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026

Xiaomi Watch S4 (including bezel and strap), Magnetic charging dock, User manual (including warranty notice)1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Package contents row.

Power adapter in boxiA mains/USB power adapter is supplied. A charging cable, inductive puck or charging dock alone does not count.

No2Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026What's in the box lists only Fitbit Versa 4, Classic band (small & large) and Charging cable. No power adapter.

No1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Package contents list only the watch, magnetic charging dock and manual. No power adapter.

Links

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Product page

store.google.com/us/product/fitbit_versa_4_specs2Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026

www.mi.com/global/product/xiaomi-watch-s42Maker product pagemi.com/global/product/xiaomi-watch-s4Read 15 October 2026

Spec sheet

store.google.com/us/product/fitbit_versa_4_specs2Maker product pagestore.google.com/us/product/fitbit_versa_4_specsRead 7 October 2026Online maker specification sheet for regulatory model FB523.

www.mi.com/global/product/xiaomi-watch-s4/specs1Maker product pagemi.com/global/product/xiaomi-watch-s4/specsRead 15 October 2026Global specs page. Base case and strap describe the Black version.

Manual

storage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsK1Owner's manualstorage.googleapis.com/support-kms-prod/aMr9HIIq7XWrbNCLHQyr9sA3nP2Y6JUWITsKRead 7 October 2026Versa 4 User Manual Version 2.1, linked from the Fitbit user manuals help page (support.google.com/googlehealth/answer/14253977).

Not available

EPREL registration numberiId in the EU energy label database. Each size or model of a series has its own id, so it is per variant.

Not available

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Warranty

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Manufacturer warranty (source market)iThe maker's warranty period for the exact SKU or configuration and market named in the source note. It applies only to that stated market, not every regional variant. Statutory consumer rights are excluded. The base term is stored. An extension that needs registration goes in the source note.

1year15Maker product pagesupport.google.com/product-documentation/answer/14815834Read 7 October 2026Manufacturer contractual warranty for original new US Fitbit Versa 4 / FB523 retail units purchased before July 11, 2023: one year. Exact US Abt FB523BKBK-US also states one-year limited parts/labour warranty. The original maker contract separately gives two years for an EEA resident purchasing in the EEA, including the retained Estonian market. This scalar applies only to the stated US source-market contract, not all variants. Later purchases use the separate Google Hardware Warranty Center terms.16Retailer pageabt.com/Fitbit-Versa-4-Graphite-Aluminum-Black-Strap-Fitness-Smartwatch-24mm-FB523BKBKUS/p/182318.htmlRead 7 October 2026Exact new US FB523BKBK-US listing states one-year limited parts and labour warranty. This source-market claim is distinct from the maker two-year EEA contract and does not set the Estonian variant warranty.

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Both are also in the API. Back to all smartwatches.