A:Answer I just wrote my review of the product and only gave it 2 stars because I've found (for me at least) it to be hit/miss on how accurate it is. Some times not matter how high, low, loose, tight I have it, the heart rate feature is WAY off! It happens just enough to make me question how accurate it is every other time of the day. In one of MANY examples I have, I was doing HIIT cardio, was completely out of breathe, sweating, heart is racing and the Fitbit says my HR was at 72bpm...in reality it was probably in the 155-175 range.