Sorry, Garmin — the Apple Watch Ultra 2 is the Most Accurate Fitness Tracker, According to a Recent Study
The Ultra 2 also beat the latest wearables from Samsung and Whoop

It wasn’t necessarily the outcome he was expecting when Rob ter Horst, a data scientist at the University of Vienna, pitted top consumer wearables from Apple, Garmin, Samsung, and Whoop against a high-end, chest-mounted heart rate monitor to compare the accuracy of each.
More specifically, ter Horst tested the Apple Watch Ultra 2 (running watchOS 26 beta) against the Garmin Forerunner 570, Garmin Fenix 7, Samsung Galaxy Watch 7, and Whoop MG fitness band. For a control, he turned to the Polar H10 chest monitor, which he refers to as his ‘gold standard’ for accuracy.
Despite the Whoop MG being listed as a medical-grade wellness device, the Apple Watch Ultra 2 bested it, along with the rest of the competition, by a notable margin. Ter Horst reports that heart rate data from the Ultra 2 is nearly a perfect match with the H10, with only slight deviations.
Apple beats Garmin, Samsung and Whoop for heart rate accuracy
The Samsung Galaxy Watch 7, meanwhile, was the second-most accurate wearable he tested, with roughly 3% deviation from the control data. The Whoop MG came in third place with 6% deviation, followed by the Garmin Forerunner 570 with 7% deviation, and lastly, the Garmin Fenix 7 with 9% deviation.
Further testing while running and cycling in an outdoor environment similarly resulted in near-perfect heart rate data from the Apple Watch Ultra 2.
Other wearables did noticeably worse when the testing moved outside. The Forerunner 570 data deviated a troubling 12% from the control, while data from the Whoop MG deviated a whopping 15%.
The Ultra 2 is also a darn-accurate sleep-tracker
In separate testing, ter Hurst also found the Apple Watch Ultra 2 to be a reasonably accurate sleep tracking device, capable of correctly identifying REM and deep sleep 73% of the time and light sleep 86.5% of the time. For this test, he used the Hypnodyne ZMax, a head-mounted sleep monitor, as the control.
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While the 73% accuracy may seem a bit low, ter Hurst notes that the opposite is true. In fact, from his testing, the Ultra 2 is a more accurate sleep tracker than most other consumer wellness wearables out there, including the Oura Ring 4 — the best smart ring available today.
What does this mean for the Ultra 3?
With all this talk of the Apple Watch Ultra 2, you may be thinking to yourself, ‘What about the Apple Watch Ultra 3?’ Well, dear reader, with an official Apple event on the calendar for September 9th, there’s a decent chance that Cupertino’s next-gen, tough-built wearable will grace us with its presence before we know it.
There’s no shortage of Apple Watch Ultra 3 rumors, including the possibility of screen upgrades, battery life enhancements, additional safety and wellness tools, and even AI features. As a result, my expectations (and excitement levels) are sky-high.
However, even if the Ultra 3 doesn’t arrive as expected, Cupertino can still sleep soundly resting on the laurels of the Ultra 2’s performance in ter Horst’s testing.
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Dan Bracaglia is the Tom’s Guide editorial lead for all things smartwatches, fitness trackers and outdoor gear. With 15 years of experience as a consumer technology journalist testing everything from Oura Rings to instant cameras, Dan is deeply passionate about helping readers save money and make informed purchasing decisions. In the past year alone, Dan has assessed major product releases from the likes of Apple, Garmin, Google, Samsung, Polar and many others.
An avid outdoor adventurer, Dan is based in the U.S. Pacific Northwest where he takes advantage of the beautiful surroundings every chance he gets. A lover of kayaking, hiking, swimming, biking, snowboarding and exploring, he also makes every effort to combine his day job with his passions. When not assessing the sleep tracking and heart rate accuracy of the latest tach gadgets, you can find him photographing Seattle’s vibrant underground music community.
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