Is Your Apple Watch Accurate? Depends on What You’re Tracking.

A 2025 meta-analysis published in Physiological Measurement evaluated 56 studies assessing the Apple Watch’s accuracy in monitoring health metrics. The findings indicate that while the device reliably measures heart rate and step counts, its accuracy in estimating energy expenditure (calories burned) is limited. 

Specifically, the study found that heart rate and step measurements generally fell within acceptable error margins. However, estimates for energy expenditure often exceeded the 10% error threshold, suggesting that users should interpret calorie burn data with caution. The accuracy of these measurements can also vary based on user characteristics and activity types.

Currently there is not a wearable on the market within the acceptable error threshold. The closest one available is the Oura Ring coming in at an error rate of 13%.