Question: how accurate is fitbit heart rate monitor?
Answer: Results: The Apple Watch 3 and Fitbit Charge 2 were generally highly accurate across the 24-hour condition. ... The Fitbit Charge 2 had a mean difference of −3.47 bpm, a mean absolute error of 5.96%, and a mean agreement of 91% when compared with the ECG across 24 hours. These findings varied by condition.