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How does the Apple Watch calculate calories burned and is it accurate?

The harder you work, the more calories your Apple Watch says you're burning.
By
March 28, 2022

Feeling the burn is especially satisfying with a calorie count right on your wrist. But can you count on it? Find out how your Apple Watch calculates the calories you burn and learn whether the stats are accurate.

Read more: Everything you need to know about the Apple Watch

QUICK ANSWER

Your Apple Watch uses information such as your height, weight, age, gender, heart rate, and movement throughout the day to calculate how many calories you burn. It's an estimation of course, but in general, the results are considered fairly accurate.


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How does the Apple Watch calculate calories burned?

The Apple Watch Series 7 heart rate sensor close up
Jimmy Westenberg / Android Authority

When you first set up your Apple Watch, you will be asked to input your age, gender, weight, and height. Meanwhile, the device itself equips various sensors to actively track your activity and heart rate. Through a series of algorithms, Apple uses this data to create a relatively accurate estimate of how many calories you are burning.

Additionally, your Apple Watch allows you to specify your activities for improved accuracy during workouts. Choosing a relevant type of workout (such as outdoor cycling, for example), enables your Apple Watch to use the appropriate sensors and data sources when estimating results. This results in specific calorie calculations for each workout type.

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Is the calculation accurate?

Once you know how the Apple Watch calculates calories burned, the next question is its accuracy. Bluntly speaking, Apple’s measurements are called estimates for a reason. Outside of an extremely controlled environment, it would be very difficult to determine your caloric burn with 100%  accuracy. However, Apple Watches are powerful tools and these estimates are largely considered dependable.

Tips for getting the most accurate results

A user enables Apple Watch Wrist Detection on her iPhone 11.
Kaitlyn Cimino / Android Authority
  • Enable Wrist Detection: Wrist Detection allows your Apple Watch to take background heart rate readings such as walking and resting rates. It also enables the device to track your Stand progress. To enable Wrist Detection, open the Watch app on your paired iPhone. Tap the My Watch tab, then scroll down to and tap Passcode. Slide the Wrist Detection toggle to the on position.
  • Choose your workout: As mentioned, your Apple watch adjusts your calorie burn calculations depending on which type of exercise you are doing. Choose the correct workout before starting to record your activity.
  • Update your data: As data points such as height, weight, and even medication use can impact the accuracy of your estimated calories, keep personal information up to date. To do so, open the Watch app on your paired iPhone and tap the My Watch tab, then scroll down to and tap Health. Tap Health Details. Finally, tap Edit, then tap the details you want to adjust.
  • Check your fit: Your Apple Watch uses data from its heart rate sensor to estimate calories during workouts. With this in mind, be sure to wear your watch appropriately. Strap on a snug fit with the device centered on the top of your wrist.
  • Calibrate your device: Maximize the accuracy of your calorie estimates by calibrating your Apple Watch. In addition to fine-tuning your distance and pace data, calibrating your watch will also help the device learn your fitness level and stride.

Read more: Fitbit vs Apple Watch — Which fitness ecosystem is best?

FAQs

What is the difference between active and resting calories?

Active calories refer to the calories an individual burns during physical activity. These are represented by the red Move ring on your Apple Watch. Resting calories are those which your body burns during inactivity. Maintaining bodily functions from breathing to digesting food burns calories, likely without you even noticing. The rate at which your body burns resting calories can be estimated based on weight, height, age, and gender.

Are any third-party calorie-tracking apps compatible with the Apple Watch?

If you are interested in tracking the calories you consume, a number of third-party calorie-counting apps offer Apple Watch compatibility, including MyFitnessPal. Read our guide comparing four of the most popular apps available.

How many calories do you need?

According to Harvard Health, most women need 1,600 to 2,000 calories per day, while the average man requires 2,000 to 2,400 calories per day. However, caloric needs are extremely personal and dependent on a number of health factors. These include age, activity level, body type and size, and goals.

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