Calibrating your Apple Watch Series 1 or earlier for improved Workout and Activity accuracy

You can calibrate your Apple Watch to improve the accuracy of your distance, pace, and calorie measurements. Calibrating your watch can also help it learn your fitness level and stride, which improves accuracy when GPS is limited or unavailable.

System Services screen on iPhone

Check your settings

To make sure that your Apple Watch has the information it needs, check these settings on your iPhone:

  1. Tap Settings > Privacy > Location Services and make sure that Location Services is turned on.
  2. Tap Settings > Privacy > Location Services > System Services and make sure that Motion Calibration & Distance is turned on.

If you have Apple Watch Series 2 or later, that's all you need to do. Your watch has built-in GPS, which allows you to get accurate information during an outdoor workout without your paired iPhone. If you need help, use these tips to improve your Workout and Activity accuracy.  

If you have Apple Watch Series 1 or earlier, continue with the calibration steps. 

Calibrate your Apple Watch Series 1 or earlier

Calibration helps improve the accuracy of walking and running workouts, both indoor and outdoor. Here's how to calibrate your Apple Watch Series 1 or earlier:


Workout app -- Outdoor Walk

  1. While wearing your Apple Watch, go to a flat, open outdoor area that offers good GPS reception and clear skies. 
  2. Bring your iPhone for GPS. Hold your iPhone in your hand, or wear it on an armband or waistband.
  3. Open the Workout app. To start, tap Outdoor Walk or Outdoor Run. To set a goal before starting, tap dots icon.
  4. Walk or run at your normal pace for about 20 minutes.

If you don't have time to finish the workout, you can complete 20 minutes over multiple outdoor Workout sessions. If you work out at different speeds, you should also calibrate for 20 minutes at each of the speeds that you walk or run.

Whenever you walk or run outside using the above steps, your Apple Watch continues to calibrate the accelerometer by learning your stride length at different speeds. Calibration can also improve the accuracy of your calorie calculations in the Workout app, and the calorie, distance, Move, and Exercise calculations in the Activity app. 

Privacy screen on iPhone

Reset your calibration data

Here's how to reset your calibration data:

  1. On your iPhone, open the Apple Watch app.
  2. Tap the My Watch tab, then tap Privacy > Reset Fitness Calibration Data. 

Improve your Workout and Activity accuracy

Your personal information, such as your height, weight, gender, and age, is one of the things your Apple Watch uses to calculate how many calories you burn and more. Learn how to update your personal information.

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