Smartwatches inaccurately estimate calorie burn, study finds

A study conducted by researchers at Florida International University has found that popular smartwatches inaccurately estimate calories burned during physical activity. The research, published in the journal ‘PLOS One’, tested the Apple Watch Series 8, Fitbit Sense 2, Samsung Galaxy Watch 5, and Garmin Forerunner 955.

Results indicated that none of the tested devices provided precise calorie counts, with typical errors ranging between 15% and 25%. The Apple Watch demonstrated the highest accuracy relative to laboratory metabolic measurements, while Garmin and Samsung significantly overestimated energy expenditure. The Fitbit device produced inconsistent results, occasionally providing unreliable or missing data.

The study also noted a correlation between body composition and inaccuracy, observing that error margins increased as the participants' body fat percentage rose. The testing involved 58 participants performing stationary cycling exercises while being monitored by a professional COSMED K5 metabolic analyzer.