Apple’s latest flagship smartwatch, the Apple Watch Ultra 2, has demonstrated high accuracy in heart rate and sleep tracking in independent tests conducted by a bioinformatics researcher. The tests compared the device with competing wearables from Garmin, Suunto, Amazfit, Samsung, Whoop, and Huawei.
During indoor running sessions, the Apple Watch Ultra 2’s heart rate sensor produced results closely aligned with a reference Polar H10 chest strap, with only minor deviations.
The performance was comparable to the Huawei Watch 5, while other devices such as the Whoop MG, Garmin Forerunner 570, Garmin Fenix 7, and Samsung Galaxy Watch 7 showed larger variances.
Outdoor running and cycling tests also demonstrated consistent results, whereas some competing devices exhibited greater deviation from reference readings.
Sleep tracking was evaluated against a Hypnodyne ZMax EEG device, which records sleep phases at approximately 72% accuracy. The Apple Watch Ultra 2 achieved roughly 73% accuracy for REM and deep sleep and 86.5% for light sleep, slightly outperforming the Oura Gen 4 Smart Ring.
Other wearables, including Samsung Galaxy Watch Ultra 2, Whoop 4.0, and Garmin Fenix 7, recorded lower accuracy in this comparison. The tests were limited to a single unit of each device and one participant, suggesting the results provide only moderate insight into overall performance across all users.