I tested the Apple Watch 12’s heart rate accuracy vs a chest strap for running, cycling, HIIT and strength workouts — here's my verdict

I recently conducted an experiment to evaluate the accuracy of the Apple Watch 12's heart rate sensor compared to a chest strap during various workouts. The Apple Watch Series 12 and Ultra 4 boast the most accurate heart rate sensor on the market, according to an in-house Apple study comparing it to other wearables using a Polar H10 chest strap as a reference.

I tested the Apple Watch 12 during running, cycling, high-intensity interval training (HIIT), and strength workouts. I paired the Apple Watch with a Garmin HRM 600 chest strap on one wrist and wore the Apple Watch 12 on the other. I used the DC Rainmaker Analyzer to compare the heart rate readings from both devices.

The Apple Watch 12 generally performed well during my runs, with only brief periods where it grayed out the heart rate reading when it lacked confidence. Overall, the Apple Watch 12's heart rate sensor remained closely aligned with the chest strap throughout my outdoor runs, including a half marathon race and various challenging workouts. It even outperformed the Apple Watch Ultra 4 in this regard.

During indoor cycling, the Apple Watch 12's heart rate accuracy was also impressive, with minimal errors and a slightly higher average heart rate reading compared to the chest strap. The watch remained accurate across different sports bands, with the nylon sport loop being the most comfortable option for me.

While the Apple Watch 12's optical heart rate sensor isn't as precise or responsive as a chest strap, it still provides a reliable estimate of heart rate for most users, especially considering its convenience and comfort. For those prioritizing accuracy during their workouts, a chest strap remains the gold standard, but the Apple Watch 12 offers a viable alternative for many.