Your phone rules out half the smartwatch market before you compare a spec. After that, the trade-offs are battery life against smart features, and which health features are available and authorized where you live. This guide walks through each one using the vendors' own published specs and FDA records, checked on 14 November 2026.
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Short answer. Pick by phone first: Apple Watch only works with iPhone, Pixel Watch and Galaxy Watch only work with Android (Galaxy works best with a Samsung phone), and Garmin works with both. Then choose a type: a full smartwatch if apps, payments and calls matter (roughly a day to two and a half days per charge on vendor claims), or a Garmin-style fitness watch if you want training features and battery measured in days. Treat health alerts, even FDA-cleared ones, as prompts to see a clinician, not diagnoses.
This is a research-based guide, not a hands-on review. The Review NYU did not test any of these watches. On 14 November 2026 we read Apple, Google, Samsung and Garmin product and support pages and two FDA records, all listed under Sources.
Samsung's US Galaxy Watch9 page did not show a battery life figure in hours when we read it, so we report only the battery capacity Samsung lists. Several pages were read as search excerpts rather than in full. We did not read FDA records for Samsung or Google features, or independent battery and accuracy tests. Battery, accuracy and feature claims below are the vendor's own.
These labels are ours, not an industry standard, but they match how vendors describe their ranges.
A full smartwatch runs apps, handles payments, voice assistants and rich notifications, and can often take calls. Apple Watch, Google Pixel Watch and Samsung Galaxy Watch are the main examples, and their battery life is rated in hours, not days. As of 14 November 2026, Apple's compare page describes Apple Watch Ultra 4, Series 12 and SE 3 as the latest models, Google's store lists Pixel Watch 5, and Samsung's US site features Galaxy Watch9 alongside Galaxy Watch Ultra.
These put training, GPS and battery first. Garmin is the obvious example: its October 2026 buyer's guide spans the Forerunner running line, the vívoactive and Venu wellness lines, and the rugged fēnix, Enduro and Instinct lines. Garmin quotes battery life in days in smartwatch mode, from up to 8 days for Venu X1 to up to 90 days for Enduro 4. Expect fewer third-party apps than on a full smartwatch.
If you mostly want steps, sleep, heart rate and message alerts, a simpler device can be lighter and last longer. Garmin's own guide lists the Lily 2 Active, which it pitches for "essential wellness tracking" with up to 9 days in smartwatch mode. Hybrids and fitness bands from other brands belong here too; we did not check those brands for this guide.
This is the first filter. A watch that does not support your phone will not set up, or will lose key features.
If you are also choosing a phone, our iPhone 17 vs Pixel 10 vs Galaxy S26 comparison covers the phone side of that decision.
Battery figures are vendor claims under vendor test conditions, not independent measurements.
| Platform and example models | Phone compatibility | Typical claimed battery | Main strengths |
|---|---|---|---|
| Apple Watch (SE 3, Series 12, Ultra 4) | iPhone only (iPhone 11 or later) | SE 3 up to 18 hours; Series 12 up to 24 hours; Ultra 4 up to 50 hours (up to 32, 38 and 84 hours in Low Power Mode) | Deep iPhone integration, wide health feature set including FDA-authorized ECG and notification features, cellular options |
| Google Pixel Watch 5 | Android 12 or newer; no iPhone support listed | Up to 30 or up to 40 hours with always-on display; up to 48 or 72 hours with Battery Saver | Wear OS with Google services, dual-frequency GPS, LTE and satellite SOS options |
| Samsung Galaxy Watch9 and Galaxy Watch Ultra | Android only; some features need Android 13+ and the Samsung Health app, some a Galaxy phone | Watch9: 390 mAh (40 mm) or 445 mAh (44 mm) battery, hours not stated on the pages we read; Galaxy Watch Ultra up to 60 hours with always-on display | Long health feature list on Android, including cuff-calibrated blood pressure estimates where available |
| Garmin (Venu 4, Forerunner 970, fēnix 9, Enduro 4) | iPhone and Android | Venu 4 up to 12 days (45 mm); Forerunner 970 up to 15 days; fēnix 9 up to 29 days (51 mm); Enduro 4 up to 90 days, all in smartwatch mode | Multi-day battery, training metrics, rugged and solar options, cross-platform |
| Slim trackers (example: Garmin Lily 2 Active) | Garmin: iPhone and Android | Lily 2 Active up to 9 days in smartwatch mode | Light, simple, fewer distractions, lower cost of entry |
Apple lists Apple Watch Series 12 from $399 and Ultra 4 from $799, and Google lists Pixel Watch 5 from $399.99, all checked 14 November 2026; prices vary by size, cellular and band.
For nightly sleep tracking, you need a daily top-up window; Google claims 15 hours of charge in 15 minutes on its Pixel Watch 5 page. If that habit will not stick, a multi-day watch is safer. For reading footnotes, see our guide on how to read a product spec sheet.
We did not read independent battery tests for these models, so treat every figure here as a vendor claim.
A smartwatch is not a medical diagnosis device. Even FDA-authorized features are screening or notification tools with stated limits, and many other metrics are labeled wellness-only.
The FDA granted Apple's ECG app a De Novo classification on 11 September 2018 as "electrocardiograph software for over-the-counter use". Apple lists it on current models, including SE 3. Google's Pixel Watch 5 spec page says its ECG app is "only available in select countries" and is not intended for people under 22. Samsung lists ECG on its Galaxy Watch Ultra page, and Garmin lists an ECG app for Venu 4. A watch ECG is a single-lead recording and does not replace a clinical ECG.
Apple lists irregular rhythm notifications and hypertension notifications on its current models. The FDA's 510(k) summary K250507 shows Apple's Hypertension Notification Feature was cleared on 11 September 2025 as a Class II device. Its indications say it is for adults 22 and over who have not been diagnosed with hypertension, that it does not replace traditional diagnosis, and that "the absence of a notification does not indicate the absence of hypertension". It also references Apple's cleared Irregular Rhythm Notification (K231173) and Sleep Apnea Notification (K240929) features. Samsung lists an Irregular Heart Rhythm Notification on its Galaxy Watch pages.
Samsung's approach is different: Galaxy Watch9 and Galaxy Watch Ultra estimate blood pressure after calibration with a separate arm cuff. Samsung's footnotes say recalibration is needed every four weeks, that availability varies by country, and that the feature "is not intended for any diagnostic purposes regarding hypertension".
Apple lists sleep apnea notifications on SE 3, Series 9 and later, and Ultra 2 and later. Samsung says Galaxy Watch9 "can also help identify signs of moderate-to-severe sleep apnea"; we did not confirm its US regulatory status for this update. Apple lists a Blood Oxygen app with an availability footnote, and Google says Pixel Watch blood oxygen readings are "not available in all countries" and are "intended for general fitness and wellness purposes". Sleep scores and "Vitals" dashboards are wellness features, not diagnostic tests.
If a health feature is why you are buying, check it against your country and phone in the vendor footnotes.
Every watch here tracks steps, heart rate, workouts and sleep; the differences are in training depth and connectivity.
Most people can narrow the field to one or two models by step three.
If an older model is on sale, our guide to buying the newest model versus last year's explains how to weigh the discount against what you give up.
No. Apple's compatibility page lists only iPhones. Current models such as Apple Watch Series 12 and Ultra 4 need an iPhone 11 or later with iOS 27 or later.
No. Google says Pixel Watch 5 works with phones running Android 12 or newer and does not list iPhone support, and Samsung's Galaxy Watch pages require an Android phone.
Fitness-first watches last far longer than full smartwatches on vendor claims. Garmin rates the Forerunner 970 at up to 15 days and the Enduro 4 at up to 90 days in smartwatch mode, while Apple rates Series 12 at up to 24 hours and Ultra 4 at up to 50 hours.
Some are FDA-authorized for specific uses. Apple's ECG app received an FDA De Novo classification in 2018 and its Hypertension Notification Feature was cleared in September 2025 for adults 22 and over without a prior diagnosis. These are screening tools, not diagnoses, and Samsung says its cuff-calibrated blood pressure estimates are not intended for diagnosing hypertension.
No. This guide is based on vendor spec pages, support pages and FDA records read on 14 November 2026. Battery and accuracy figures are vendor claims.