Hi
Keep in mind that Apple Watch displays Active Energy (calories) on the watch, rather than total calories. Also, the heart rate sensor is likely to give better results for workouts that involve rhythmic (eg running) rather than irregular (eg tennis) movements.
The following steps may help to improve the accuracy of heart rate readings and/or of estimations for calories and other results:
Check that your iPhone and watch are updated with the latest software:
Check that your personal information is accurate:
- On your iPhone, in the Watch app, go to: My Watch (tab) > Health > check and, if necessary, edit your birthdate, gender, height and weight.
During workouts, for the best performance from the heart rate sensor (data from which is also used when estimating calories), ensure that you wear your watch snugly on the top of your wrist.
- Apple suggests that you consider tightening the band before starting a workout and loosening it again afterwards.
Even under ideal conditions, various factors may prevent Apple Watch from recording consistent heart rate readings every time for everybody. For example, a user may have wrist tattoos and/or or low skin perfusion (which can also be affected by cold temperatures). Under such circumstances, Apple suggests that you consider pairing your watch with an external heart rate monitor.
Calibrate your watch, which will improve the accuracy of health and activity-related estimations including:
More information:
