Apple Shares Study Data Behind Apple Watch Series 12 Heart Rate Claim

Apple describes Health Sensing System as a major upgrade for Apple Watch. It includes updated electrical and optical photoplethysmography heart sensors and associated signal processing algorithms, as well as features enabled by the new technology, such as Recovery HRV and the Readiness app, according to Apple.

According to 9to5Mac, the study's testing took place across five sites in the United States and Malaysia during July and August 2026. Apple enrolled 1,460 adults, and 1,254 contributed at least one paired measurement to the final analysis. Participants wore Apple Watch Series 12 on one wrist and a competing wrist-based device on the other. A Polar H10 ECG chest strap served as the reference.

Apple compared Series 12 against the Garmin Forerunner 970, Google Pixel Watch 4, Huawei Watch 5, Samsung Galaxy Watch 8 and WHOOP 5. Participants also wore an Oura Ring 5 on an index finger, following Oura's guidance. The tests covered outdoor running, treadmill intervals, cycling, high-intensity interval training and strength training. Apple also measured background heart rate during everyday activities including resting, desk work, meal preparation and walking.

The scenarios included challenges such as rapid wrist movement, changing heart rates and the "cadence lock" that can cause an optical sensor to mistake running rhythm for a pulse.

Apple says Series 12 produced statistically better accuracy than every comparison device across both workouts and daily living. Across 159 individual activity and measurement comparisons, Apple Watch achieved statistically better accuracy in 139.

The report links to the full study and results. Apple Watch Series 12 is currently available for pre-order from $399. Apple Watch Ultra 4 is available for pre-order from $799. Both models launch in one week on September 18.

Editor's Summary

Apple's new study supports its claim that Apple Watch Series 12 and Apple Watch Ultra 4 have the most accurate heart rate sensing in a wearable. The research, conducted across five U.S. and Malaysian sites, compared Series 12 with several competing wrist devices and an Oura Ring 5 using a Polar H10 chest strap as reference. Apple says Series 12 was statistically more accurate in 139 of 159 comparisons, as both models approach their September 18 launch.