A recent study reveals that popular smartwatch models tend to overestimate calories burned, with errors ranging from 15% to 25%, casting doubt on the precision of these devices for tracking energy expenditure.
Smartwatch calorie counts are useful as rough guides, but they are not precise measurements of energy expenditure. A Florida International University study found that four widely used devices , the Apple Watch Series 8, Fitbit Sense 2, Samsung Galaxy Watch 5 and Garmin Forerunner 955 , all overstated calories burned, with average errors ranging from 15% to 25%.
The researchers tested 58 participants in a controlled setting, pairing each watch with a Cosmed K5 metabolic analyser and an electrocardiogram chest strap to measure heart rate. Age, sex, height and weight were entered into the devices before participants completed exercise on a stationary machine. Apple’s watch produced the smallest error in the study, while Samsung and Garmin showed larger overestimates. Fitbit also had enough technical problems during testing that some of its data had to be excluded.
The findings suggest the gap between smartwatch estimates and actual energy use may widen for some users, particularly as body fat increases, although the researchers have not yet identified the reason. Jason Kostrna, the study’s lead author and an associate professor of kinesiology and exercise science at FIU, warned in a press release that users could be “hundreds of calories off each week” if they rely on the figures too literally. For now, the best approach is to treat calorie read-outs as directional rather than exact, and to weigh them alongside appetite, body composition and how you feel during the day.
Disclaimer: This content is intended for informational purposes only. Readers are advised to exercise their own judgement, conduct due diligence, or consult a qualified expert before acting on any information provided.
