Smartwatches
every smartwatch and gps fitness watch we track, one row each. filter by the works-with column first, then sort by battery or gps hours to see how long each one lasts between charges. open a cell's caveat when a number looks too good, because the makers don't all measure battery the same way.
 Amazfit Active 2 (44mm, Round) | 7.3 A five-star budget pick with a steel case and bright screen that punches far above its price, with some rough software edges. | 10 days Amazfit claim for typical use; heavy use up to 5 days, battery saver up to 19 days. | 21 h Amazfit's 'Continuous GPS Usage' figure. | 5 ATM | Amazfit lists 5 satellite systems with no dual-band support, unlike its Balance and T-Rex spec sheets. | No ECG app; the standard (sport strap) version also lacks NFC, which needs the Premium version. | iPhone + Android Requires Android 7.0+ or iOS 14.0+; typed message replies work on Android only. |
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 Amazfit Balance 2 | 7.4 Hits its three-week battery claim with accurate dual-band GPS and health sensors, but Zepp OS lacks major third-party apps. | 21 days Amazfit claim for typical use; heavy use is rated at up to 10 days. | 33 h Amazfit publishes GPS runtimes only for 'Accurate GPS Mode' (dual-frequency, all satellites) and a single-frequency 'Power Saving GPS Mode'; no standard single-band figure exists, so the Accurate GPS Mode figure is used (the power-saving figure is a low-power mode). Power Saving GPS Mode is rated at up to 67 hours. | 10 ATM 10 ATM per ISO 22810:2010; Amazfit also rates it for 45 m freediving and recreational scuba. | No ECG app listed on Amazfit's spec sheet. | iPhone + Android Requires Android 7.0+ or iOS 15.0+; typed message replies work on Android only. | |
 Amazfit T-Rex 3 Pro (48mm) | 7.7 Outstanding value: titanium, sapphire, weeks of battery and accurate GPS, let down by thin app support and no ECG. | 25 days 48mm typical-use claim; heavy use up to 10 days. The 44mm version is rated at up to 17 days. | 38 h Amazfit publishes GPS runtimes only for 'Accurate GPS Mode' (dual-frequency, all satellites) and a single-frequency 'Power Saving GPS Mode'; no standard single-band figure exists, so the Accurate GPS Mode figure is used (the power-saving figure is a low-power mode). 48mm: Power-Saving GPS Mode up to 74 hours, GPS Long Battery Life Mode up to 85 hours. | 10 ATM 10 ATM; certified for diving to 45 m (freediving and scuba). | No ECG app; TechRadar also lists missing ECG among its omissions. | iPhone + Android Requires Android 7.0+ or iOS 15.0+; typed message replies work on Android only. | |
 Apple Watch SE 3 44mm (GPS) | 7.9 The cheapest good way into Apple Watch, now with always-on display, but an 18-hour battery and no ECG keep it a step behind. | 0.8 days Apple rates up to 18 hours of normal use; up to 32 hours in Low Power Mode. | 7 h Apple: up to 7 hours workout tracking, tested during outdoor runs without iPhone, heart rate sensor on. | 5 ATM | L1 GPS only (no L5). | No ECG app on SE models; irregular rhythm notifications only. | iPhone only |
 Apple Watch Series 11 46mm (GPS) | 8.6 The best smartwatch for iPhone owners by a distance, with polished software and health features, held back only by needing a charge every day. | 1 days Apple rates up to 24 hours, a figure that includes 6 hours of sleep tracking; up to 38 hours in Low Power Mode. | 8 h Apple: up to 8 hours outdoor workout with full GPS and heart rate readings, tested without iPhone. | 5 ATM | L1 GPS only (no L5). | iPhone only | |
 Apple Watch Ultra 3 49mm (GPS + Cellular) | 8.5 Apple's most capable watch, with a huge bright screen, dual-band GPS and satellite SOS, but it is bulky and only pays off with an iPhone. | 1.8 days Apple rates up to 42 hours of normal use (includes 6 hours of sleep tracking); up to 72 hours in Low Power Mode. | 14 h Apple: up to 14 hours outdoor workout with full GPS and heart rate readings; 20 hours with Low Power Mode, 35 hours with Low Power Mode plus fewer GPS readings. | 10 ATM Rated 100 m (ISO 22810:2010) and for recreational scuba to 40 m. | iPhone only | ||
 Fitbit Sense 2 | 5.8 Rich wellness sensors including ECG and skin temperature, but 2022 hardware stripped of third-party apps and music. | 6 days Google rates it '6+ days'; up to 3 days with the always-on display. SpO2 and cEDA use shorten it. | 12 h Google's Fitbit battery support article says up to 12 hours with continuous GPS; the Google Store spec page lists 'up to 5 hours with continuous GPS', so treat 12 as a best case. | 5 ATM Water resistant to 50 m. | Built-in GPS + GLONASS, single-frequency. | ECG app for AFib assessment ('not available in all countries'; available in the US). | iPhone + Android Requires iOS 16.4+ or Android 11+. |
 Fitbit Versa 4 | 5.3 Comfortable with good sleep tracking, but its heart rate read low in testing and Google removed apps, music and Assistant. | 6 days Google rates it '6+ days'; up to 3 days with the always-on display. | 12 h Google's Fitbit battery support article: up to 12 hours with continuous built-in GPS. | 5 ATM Water resistant to 50 m. | Built-in GPS + GLONASS, single-frequency. | No ECG app (the Sense 2 has it). | iPhone + Android Requires iOS 16.4+ or Android 11+; on-wrist calls are Android-only per Tom's Guide. |
 Garmin fenix 8 AMOLED 47mm | 8.2 Best-in-class for ultras and thru-hikes with the longest GPS battery here, but the highest price in its class and fiddly charging cable. | 16 days Garmin claim with gesture-wake display; 7 days with always-on display. | 47 h GPS-only with gesture display; 37 hours with always-on display. | 10 ATM 10 ATM; also rated for recreational diving (EN 13319, 40 m). | Garmin ECG app; region availability varies. | iPhone + Android | |
 Garmin Forerunner 570 47mm | 7.6 Accurate and bright with dual-band GPS, but priced near the 970 while skipping ECG and maps, and the older 265 lasts longer for less. | 11 days 47mm claim; the 42mm size is rated 10 days. Garmin lists no always-on figure. | 18 h GPS-only claim is 18 hours for both sizes. | 5 ATM | No ECG app; Tom's Guide and DC Rainmaker both note it lacks ECG despite the Gen5 sensor. | iPhone + Android | |
 Garmin Forerunner 970 47mm | 8.9 The most complete training watch here: chest-strap-grade heart rate and near-perfect GPS per DC Rainmaker, plus ECG, though it costs a lot and lost battery versus the 965. | 15 days Garmin claim with gesture-wake display; Garmin lists no always-on figure, and DC Rainmaker measured about 2.5 days with always-on at default brightness. | 26 h GPS-only; 21 hours in All-Systems + Multi-Band mode. | 5 ATM | Garmin ECG app; region availability varies. | iPhone + Android | |
 Garmin Instinct 3 AMOLED 45mm | 7.9 Rugged, bright and very long-lasting with accurate multi-band GPS, but no offline maps and the older heart rate sensor. | 18 days Garmin claim with wrist-gesture display; 7 days with always-on display. | 32 h GPS-only; 23 hours in All-Systems + Multi-Band with SatIQ. | 10 ATM | No ECG; DC Rainmaker notes it uses the Gen4 heart rate sensor, and ECG requires Gen5. | iPhone + Android | |
 Garmin Venu 4 45mm | 8.4 A do-it-all Garmin that pairs with any phone, lasts about ten days in real use and adds ECG, missing only maps and LTE. | 12 days Garmin claim with gesture-wake display; 4 days with always-on display. The 41mm size is rated 10 days. | 20 h GPS-only figure for the 45mm; 41mm is rated 15 hours. | 5 ATM | Garmin ECG app; region availability varies. | iPhone + Android | |
 Garmin Venu Sq 2 40mm | 6.1 Long battery and good heart rate in an affordable package, but it is the oldest watch here, with no altimeter and slow GPS lock. | 11 days Garmin claim with default display; Live Science measured heavy drain with always-on mode enabled. | 26 h | 5 ATM | Single-band GNSS; no multi-band listed on Garmin's spec sheet. | Not listed on Garmin's spec sheet. | iPhone + Android |
 Garmin vivoactive 6 42mm | 7.5 A slim, comfortable value Garmin with over a week of battery, held back by single-band GPS and the older heart rate sensor. | 11 days Garmin claim with gesture-wake display; 5 days with always-on display. | 21 h | 5 ATM | Single-band GNSS only; TechRadar lists no multi-band GPS as a drawback. | Not listed on Garmin's spec sheet; uses the Elevate Gen4 heart rate sensor. | iPhone + Android |
 Google Pixel Watch 4 45mm (Wi-Fi) | 8.1 The most polished Wear OS watch, with a bright display, fast charging and a repairable build, though full insights need a Fitbit Premium subscription. | 1.7 days Google rates up to 40 hours with always-on display; up to 72 hours with Battery Saver. | – Google does not publish a GPS workout figure; Android Central measured roughly 8 to 10 hours of dual-band GPS running. | 5 ATM | Android only Requires Android 11 or newer, a Google Account and the Pixel Watch app. | ||
 Polar Grit X2 Pro | 6.8 Strong outdoor battery and free offline maps, but DC Rainmaker calls it only good enough for the price, with inconsistent interval heart rate. | 10 days Polar product page: up to 10 days in smartwatch mode with continuous HR and notifications. The user manual's spec page lists 11 days. | 43 h Polar's 'Performance' training mode (dual-frequency GPS, 1 s recording, optical HR); Polar publishes no standard single-band figure. The user manual lists 40 hours for the same mode. Eco mode (single-frequency, 2 min recording) is 110 to 140 hours. | 10 ATM WR100 (100 m), for frequent use in water but not scuba. | Wrist ECG records a resting single-lead trace (HR, HRV) exportable as PDF; per DC Rainmaker it does not detect AFib and is not FDA-cleared. | iPhone + Android Polar Flow app on iOS and Android. | |
 Samsung Galaxy Watch Ultra (2025) 47mm (LTE) | 7.6 Samsung's longest-lasting, toughest watch with good dual-band GPS, but heavy, no faster than the standard model, and Samsung-phone-dependent for health features. | 3.3 days Samsung rates up to 80 hours with Always On Display off; up to 60 hours with it on; up to 100 hours in Power saving mode. | – Samsung only publishes up to 48 hours in Exercise power saving mode (a reduced-accuracy max-battery mode); no standard-GPS figure. | 10 ATM | ECG runs in the Samsung Health Monitor app, which Samsung says is only available on Samsung Galaxy phones. | Android only Android only; no iPhone support. | |
 Samsung Galaxy Watch8 44mm (Bluetooth) | 7.4 Slim with great sleep insights and Gemini, but short battery, a proprietary strap system and reviewers steering buyers to the Classic. | 1.7 days Samsung rates up to 40 hours with Always On Display off; up to 30 hours with it on. | – Samsung does not publish a continuous-GPS workout figure for this model. | 5 ATM | ECG runs in the Samsung Health Monitor app, which Samsung says is only available on Samsung Galaxy phones. | Android only Requires Android 12 or later; no iPhone support. | |
 Samsung Galaxy Watch8 Classic 46mm (Bluetooth) | 7.8 The Galaxy Watch to buy, with the rotating bezel and better battery than its sibling, though it is chunky and its ECG needs a Galaxy phone. | 1.7 days Samsung rates up to 40 hours with Always On Display off; up to 30 hours with it on. | – Samsung does not publish a continuous-GPS workout figure for this model. | 5 ATM | ECG runs in the Samsung Health Monitor app, which Samsung says is only available on Samsung Galaxy phones. | Android only Requires Android 12 or later; no iPhone support. | |
 Withings ScanWatch 2 (42mm) | 6.6 A real-looking hybrid that truly lasts a month with FDA-cleared ECG, but it has no GPS, a tiny screen and deeper insights cost a subscription. | 35 days Withings' US page now says 'up to 35 days'; older listings (including Amazon's title) say 30 days. | – No built-in GPS. The hybrid watch uses connected GPS from the phone, so Withings publishes no GPS runtime. | 5 ATM 5 ATM (50 m), 'swimproof'. | No onboard GNSS receiver. | Withings ECG App is FDA-cleared (510(k) K240795) for AFib detection from a single-lead ECG. | iPhone + Android Withings lists 'iOS & Android compatible'. |
How the AI score works, and who wrote it
A language model rated these, not a test lab. Every score from 1 to 10 is an AI assessment of how good the product is against the other 21 in this comparison, formed from the specifications we verified plus the published lab reviews and owner reception found while researching each one. Nobody at Slopsheets listened to, wore or plugged in any of it.
It weighs the things a spec table cannot show: how a product is actually reviewed, how well the software works, build quality, and what you get for the money. That is deliberate. An earlier version of this column was pure arithmetic on the table and it ranked a bundle of cheap boxes above a class-leading single unit, because counting hardware is not the same as judging it.
Treat it as an informed starting point and read the sourced comparison, not as a verdict. The score is relative to this comparison only, so it means nothing across categories, and it carries no price, star rating or review count. Every specification behind it is sourced and checked; the score on top of them is opinion.
Frequently asked questions
Which column should I look at first on this smartwatch sheet?
Works With. A watch that won't pair with your phone is out no matter how well it scores, and that column alone removes the Apple rows for Android owners and the Samsung and Google rows for iPhone owners. Sort what's left by battery or AI score.
How should I read a blank GPS battery cell?
A blank means the maker publishes no standard GPS workout figure, not that the watch lacks GPS. The one exception is the Withings ScanWatch 2, which has no GPS receiver and uses the phone's location. Each blank cell carries a note saying which case it is.
Why do some watches show a GPS figure for dual-band mode instead of standard GPS?
Amazfit and Polar only publish GPS runtimes for their dual-frequency modes and their low-power modes. We list the dual-frequency figure and flag it, since it is the closest to a normal accurate track and normally the harder test on the battery.
Is the highest battery number always the longest-lasting watch?
Within a brand, yes. Across brands, not reliably: Apple counts sleep tracking in its figure, Garmin rates its AMOLED watches with the screen waking on a gesture, and Samsung and Google differ on whether the always-on display is lit. The caveat on each cell tells you which basis applies.
What does the AI score on this sheet reward?
How each watch is reviewed overall: software, accuracy in testing, build, battery against its claim, and value for money, judged against the other watches on this sheet only. A cheap watch that punches above its price can outrank an expensive one with weaker software.