The best fitness trackers are all vying for our love and money, but it’s not often we see a whole host of them pitted against one another in what is essentially a lab setting.
Rob ter Horst, a data scientist at the University of Vienna and YouTube creator, has taken a look at Apple’s upcoming watchOS 26 update via the public beta, running it on an Apple Watch Ultra 2. He’s pitted the Ultra 2 against a series of historic heart rate data he’s collected from fitness tracker rivals like the Whoop MG and various Garmin watches, pitting them against his gold standard, the Polar H10 chest strap, to determine accuracy.
And, in a surprise twist, it’s Apple’s premium rugged watch that comes out on top, beating almost every other modern fitness tracker for heart rate accuracy.
Apple Watch Ultra 2’s health tracking dominates the competition for accuracy

For testing, ter Horst used a Polar H10 to track heart rate data for an indoor running workout, using it as his control measurement for the purposes of comparison.
Despite some small deviations, the Apple Watch Ultra 2’s heart rate sensor did a great job of matching up to the control device. Perhaps most surprisingly, it was more accurate than the Whoop MG, a device literally named ‘Medical Grade’, which deviated around 6% from the H10.
The Samsung Galaxy Watch 7 deviated just 3%, while the Garmin Forerunner 570 and Fenix 7 deviated 7% and 9% respectively.
When it comes to other workouts, the Apple Watch Ultra 2 matches up almost entirely to the Polar H10 for both cycling and outdoor runs, while rivals like the Whoop MG deviated 15%. That’s more than the Garmin Forerunner 570’s data, which deviated 12%.
It’s not just heart rate, either. According to ter Horst’s testing, the Apple Watch Ultra 2 is around 73% accurate for tracking REM and deep sleep, and 86.5% accurate for light sleep tracking when compared to a Hypnodyne ZMax as a control device.
That puts it ahead of even an Oura Gen 4 ring, while Samsung, Whoop, and Garmin’s device data falls short in this regard, too.
Where does the Apple Watch Ultra go from here?
Rumors have been swirling for a while about an upgraded Ultra 3 at Apple’s next big device launch in a little over a week at the time of writing, with suggestions that it will offer an improved display and 5G connectivity.
It’s also reportedly going to add detection for high blood pressure, adding to its toolkit of health and fitness features.
One of the biggest issues with Apple Watch (Ultra or otherwise) remains battery life, though. We’re hopeful Apple can find a way to make the sensors included more energy efficient, especially since much cheaper rivals have the tech giant beat in terms of running for weeks on a single charge.
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