If you are concerned that your Activity app estimations are inaccurate, then it may help to follow these steps:
If you have not yet done so, update your iPhone and Apple Watch to the latest software, starting with your iPhone:
Check your personal information:
- Calorie estimations depend, in part, on your personal information.
- To check that this is accurate - and to update it over time:
- On your iPhone, in the Watch app, go to: My Watch (tab) > Health > Edit - tap and adjust items, then tap on Done.
Note that Apple Watch can pair and sync with compatible gym equipment, by following the instructions here:
When recording specific fitness activities, be sure to use the Workout app and to choose the activity type that most closely matches your workout, including choosing Indoor Cycle for spin sessions:
- This enables your watch to use the most appropriate sensors and data sources when tracking results.
- Choose Other for any workouts that are neither included within, nor sufficiently similar to, those in the list of main activity types (for which Apple Watch provides tailored calorie calculations).
- Work out with your Apple Watch - Apple Support
Close certain apps and then restart (normally) both your iPhone and your Apple Watch:
If you have previously used any third-party fitness tracking, sleep tracking or heart rate monitoring apps:
- Check the developers' support resources and/or contact the developers to check for any known issues affecting how data is shared to the Health app on your iPhone.
- Check whether there is an active or paused session within any of them.
- If there is, then end that session from within that app on your Apple Watch.
- If in doubt, then it may help to remove any such third-party apps from your Apple Watch, at least temporarily.
For the best performance from the heart rate sensor (data from which is used when estimating Active calories), check that you are wearing your Apple Watch sufficiently snugly on the top of your wrist:
Other issues that can impact sensor performance include skin perfusion and wrist tattoos:
Prior to calibrating your Apple Watch (see the next step), check your Location Services settings:
- On your iPhone, go to: Settings > Privacy > Location Services:
- Check that Location Services (the main setting at the top) is turned on.
- In the list of apps beneath, if Apple Watch Workout is listed, then set it to While Using.
- Also enable options under System Services including Motion Calibration & Distance, Wi-Fi Networking and Mobile Network Search.
Calibrate your Apple Watch, resetting any existing calibration data and starting afresh:
If the issue persists, then it may help to unpair and re-pair your Apple Watch:
If the issue persists, then I suggest that you contact Apple Support (remote diagnostics and/or mail-in service may be available, if required), make a Genius Bar reservation or visit an Apple Authorised Service Provider for assistance: