Smartwatch accuracy varies in GPS, heart rate, and calorie tracking

Comparative tests and academic research have highlighted varying levels of accuracy in smartwatch metrics, particularly regarding calorie consumption and vital signs.

A practical test comparing the Apple Watch Ultra 4 and the Samsung Galaxy Watch Ultra 2 during a half-marathon showed high precision in GPS and heart rate tracking. Both devices recorded similar distances and heart rates, with the Apple Watch registering an average of 159 bpm and the Samsung model 160 bpm, compared to a reference Oura Ring 5 reading of 163 bpm.

However, a study from Florida International University revealed significant issues with calorie estimation. Researchers found that smartwatches often overestimate calorie burn, with Garmin and Samsung showing systematic overestimations. The study noted that accuracy decreases as body fat percentage increases, suggesting that many device algorithms are primarily calibrated for leaner individuals. This discrepancy is attributed to both algorithmic limitations and increased soft-tissue movement at the wrist in overweight users.