How Accurate Are Fitness Wearables? A Look at Validation Studies

Step counts are generally reliable; calorie estimates and sleep stages are less so.

Consumer wearables report a long list of metrics. Validation research shows they are not equally accurate.

Heart rate at rest and step counts tend to perform reasonably well against reference methods in independent testing.

Energy expenditure estimates frequently show large errors, and sleep staging is only moderately aligned with laboratory polysomnography.

Wearables are most useful for tracking personal trends over time rather than precise single readings. They are not diagnostic devices.

Treat a wearable as a trend line, not a laboratory instrument.

Editorial note: this article summarises published research for general information. It is not medical advice. Discuss any intervention with a qualified clinician.