Change settings in Workout on Apple Watch
Update your height and weight
Go to the Apple Watch app on your iPhone.
Tap My Watch, go to Health > Health Details, then tap Edit.
Tap Height or Weight, then adjust.
Your Apple Watch uses the information you provide about your height, weight, sex, age, and wheelchair status to calculate how many calories you burn, how far you travel, and other data. The more you run with the Workout app 
, the more your Apple Watch learns your fitness level—and the more accurately it can estimate the calories you burned during aerobic activity.
Your iPhone GPS allows your Apple Watch to achieve even more distance accuracy. For example, if you carry your iPhone while using the Workout app on a run, your Apple Watch uses the iPhone GPS to calibrate your stride. Then later, if you’re not carrying your iPhone, or if you’re working out where GPS is unavailable (for example, indoors), your Apple Watch uses the stored information about your stride to measure distance.
Apple Watch may use the built-in GPS to calibrate your movement.
Calibrate your Apple Watch
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.
While wearing your Apple Watch, go to a flat, open outdoor area that offers good GPS reception and clear skies.
Go to the Workout app, then tap Outdoor Walk or Outdoor Run. To set a goal before starting, tap
.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.
To reset your calibration data, see Calibrate your Apple Watch for improved Workout and Activity accuracy.
Change measurement units
If you prefer meters to yards or kilojoules to calories, you can change the measurement units the Workout app uses.
Open the Settings app
on your Apple Watch.Tap Workout, scroll down, then tap Units of Measure.
You can change units for energy, pool length, cycling workouts, and walking and running workouts.
Pause running and cycling workouts automatically
Open the Settings app
on your Apple Watch.Tap Workout, tap Auto-Pause, then turn on Auto-Pause.
Your Apple Watch automatically pauses and resumes your outdoor running and cycling workouts—for example, if you stop to cross the street or get a drink of water. You can manually pause your workouts by pressing the side button and Digital Crown at the same time.
Turn End Workout Confirmation on or off
When you’re finished working out, you can get a confirmation that you’re ready to end your workout.
Open the Settings app
on your Apple Watch.Tap Workout, then turn on End Workout Confirmation.
Turn workout reminders on or off
For walking, running, swimming, and other workouts, your Apple Watch senses when you’re moving and alerts you to start the Workout app. It even gives you credit for the exercise you’ve already done. It will also remind you to resume if you’ve paused your workout, and end your workout, in case you get distracted when you’re cooling down. Follow these steps to turn workout reminders on or off.
Open the Settings app
on your Apple Watch.Tap Workout, then change the Start Workout, Resume Workout, and End Workout reminder settings. (Workout reminders are on by default.)
You can also open the Apple Watch app on your iPhone, tap My Watch, tap Workout, then change the workout reminder settings.
Avoid accidental taps
If the exercise you’re doing or the gear you’re wearing causes accidental taps on your Apple Watch, turn on theater mode so your workout isn’t interrupted.
Conserve power during a workout
You can extend battery life during Apple Watch workouts.
Open the Settings app
on your Apple Watch.Tap Workout, then turn on Low Power Mode.
During workouts, Low Power Mode turns off Always On Display, background heart rate and blood oxygen measurements, and heart rate notifications. Other notifications may be delayed, emergency alerts may not arrive, and certain cellular and Wi-Fi connections are limited.
Tip: To extend battery life even further while performing walking, running, and hiking workouts on Apple Watch, turn on Low Power Mode, then turn on Fewer GPS and Heart Rate Readings. Doing so reduces the frequency of GPS and heart rate readings, and turns off alerts, splits, and segments. (Low Power Mode isn’t available on Apple Watch Series 6 or Apple Watch Series 7.)
For more information, see the Apple Support article Get the most accurate measurements using your Apple Watch.