Q: Calorie

Hi

Apple has not disclosed the algorithms / formulae used by the health and fitness apps on iPhone and Apple Watch.

Your watch can use various sensors and data sources when estimating your calories and other results. In some cases, it will rely on your arm motion to estimate your walking pace and, in turn, calories burned. In other cases, it may use data from the heart rate sensor and/or your iPhone.

For example: if you record a workout using the built-in Workout app and choose Outdoor Walk or Outdoor Run, the watch can use sources including the accelerometer, heart rate sensor and, if you also take your iPhone with you, Location Services (GPS) data (to help estimate your distance and pace).

This will also help to calibrate your watch, which may improve the accuracy of various estimates made by the Activity app and Workout app.

More information:

Use the Activity app on your Apple Watch - Apple Support

Use the Workout app on your Apple Watch - Apple Support

Calibrating your Apple Watch for improved Workout and Activity accuracy - Apple Support

For the most accurate results from calorie estimations, check that your personal information is accurate and that you keep it updated over time.

- On your iPhone, in the Watch app, go to: My Watch (tab) > Health > check and, if necessary, edit your birthdate, gender, height and weight.