If you depend on your fitness tracker to calculate calories burned, brace for disappointing news from a rigorous Stanford University study.
The research tested seven leading devices: Apple Watch, Basis Peak, Fitbit Surge, Microsoft Band, Mio Alpha 2, PulseOn, and Samsung Gear S2.
The Fitbit Surge was the most accurate at 27% deviation, but PulseOn missed by 93%. Avoid blindly trusting these estimates—you may burn fewer calories than shown.
Such variances make sense: bodies differ, algorithms can't perfectly fit all. Arm swings in activities like tennis can inflate readings. Heart rate sensors, however, were spot-on.
