How to calibrate your Apple Watch

On a clear day, wear your Apple Watch to a flat, pedestrian-friendly outdoor area with reliable GPS reception. If you have an Apple Watch Series 1 or earlier, you need to bring your paired iPhone for connected GPS.

• On your paired iPhone, open the Settings app, then scroll down to and tap Privacy. Tap Location Services and check to see if it is enabled. If not, tap the toggle.
• On the same screen, scroll down to and tap System Services. Look for Motion Calibration & Distance and make sure it is enabled. If not, tap the toggle.
• Open the workout app on your Apple Watch and begin an Outdoor Walk or Outdoor Run.
• Begin walking or running, according to the workout chosen, and keep pace for 20 minutes.
• When possible, repeat with the opposite workout.

Your Apple Watch continuously calibrates its accelerometer by learning your stride length at different speeds whenever you record a walk or run outside.

Why calibrating your Apple Watch matters

If you are hooked on tracking stats, you probably want them to be accurate. Calibration can improve the accuracy of your calorie calculations during a workout, plus influence the calorie, distance, and move calculations in your everyday activity. It can also keep data accurate when GPS is limited by helping the device learn your stride and fitness level. In short, learning how to calibrate your Apple Watch is simple, with long-lasting benefits.

How to reset your calibration data on your Apple Watch

If you want to calibrate your device from a clean slate, you can reset your calibration data from your paired iPhone. This will permanently delete your current data and history and result in less accurate measurements until you calibrate again.

• On your paired iPhone, open the Watch app.
• Tap the My Watch tab, then scroll down to and tap Privacy. Tap Reset Fitness Calibration Data, and tap it again to confirm.
• Follow the steps above for how to calibrate your Apple Watch.

Read more: How does the Apple Watch calculate calories burned?

FAQs

Can I reset my Apple Watch calibration data from the watch itself?

No. You will need your paired iPhone to reset your calibration data.

Does my Apple Watch calibrate automatically?

As mentioned above, your device will continue to automatically calibrate over time. With this in mind, it’s important to always pick the correct workouts, and keep personal information such as weight, height, age, and gender up to date.

How does my Apple Watch calculate calories burned?

Your Apple Watch uses personal information such as your height, weight, age, gender, heart rate, and movement throughout the day to calculate how many calories you burn. Read more about this calculation and its accuracy here.

Can fit affect the accuracy of my Apple Watch?

Absolutely. Wearing your Apple Watch too tight or loose can affect the accuracy of your heart rate sensor. Likewise, wearing your Apple Watch too high on your arm, or the underside of your wrist, will also affect accuracy.