
Fitbit Air: solid heart-rate tracking, but calories miss the mark
A ZDNET test compared the Fitbit Air to a Polar H10 chest strap during a gym workout. Heart-rate data were fairly close with minor lag, but calories burned were consistently underestimated—about 12% during treadmill work and up to ~30% during strength training. The results reflect how wrist wearables can miss rapid heart-rate changes and rely on formulas that combine HR with other factors, so use HR data for training and calorie estimates as rough figures. The author cautions that two tests aren’t enough to draw sweeping conclusions about overall accuracy.













