GoKawiilFIU study finds smartwatches overestimate calories burned by up to 25%
Florida International University researchers tested the Apple Watch Series 8, Fitbit Sense 2, Samsung Galaxy Watch 5 and Garmin Forerunner 955 against a Cosmed K5 metabolic device and ECG chest strap during controlled workouts with 58 participants. All four smartwatches overstated calorie burn, with margins of error ranging from 15% to 25%, meaning a reported 200-calorie burn could really be closer to 160-174 calories. Apple Watch was the most accurate, while Samsung and Garmin overestimated more, and Fitbit had enough tracking glitches that some of its data had to be excluded.