What to Know

Apple Watch calories are accurate as long as your height and weight are correctly noted in the Health app.
You should also calibrate Apple Watch's motion and distance tracking for improved accuracy.
Finally, make sure your Apple Watch fits properly for the most accurate results.

Are Apple Watch Calories accurate? Yes, the Apple Watch is quite accurate at calculating calories burned as long as you use the correct settings. We'll teach you how to improve your Apple Watch calorie accuracy by updating your height and weight in the Health app, recalibrating your watch, and making sure you are wearing it correctly.

How Accurate Are Apple Watch Calories?

This question can be asked and answered in two parts. First, how accurate is Apple's measurement of basal metabolic rate (BMR), or the calories used as determined by your age, gender, and size? The answer is that this calculation is pretty accurate. BMR science is commonly used in the medical field, and the indicators used by Apple in making this calculation are industry-standard.

Next, how accurate is the Apple Watch calories expenditure tracking? A study conducted in 2017 by Stanford University found Apple Watch to be the best in its class out of 60 other competitors for energy expenditure tracking, with the best heart rate tracking and top movement tracking.

While a medical device such as a calorimeter may be better at tracking calories used, the Apple Watch is close to being one of the best devices to track calories burned by heart rate. It is crucial, however, that your watch is set up correctly to ensure that calories are tracked as precisely as possible.

Now you know that an Apple Watch calories burned accuracy is about as good as you can get with this level of ease of use. If you are actively trying to close your Move rings but are struggling to reach the automatically assigned number, read this on how to change exercise minutes on Apple Watch so that your goals match your personal needs and keep you motivated!

Active Calories vs. Total Calories

What's the difference between active calories and total calories, and does the Apple Watch track both? Calories are burned in two ways: through your body maintaining itself at rest, and through additional calories used during exercise. Active Calories is what Apple calls the additional calories used during exercises. Total Calories is equal to Active Calories plus BMR, or the sum total of calories burned at rest and calories burned during exercise. Next, learn more about the active calories vs total calories.

How Accurate Are Apple Watch Calories?

How Does Apple Watch Calculate Calories Burned?

The Apple Watch calculates calories burned using your heart rate. To elaborate, the Apple Watch calorie counter tracks your heart rate and movement and uses your personal health information, such as height and weight, to track your daily calorie expenditure. Apple Watch calorie calculations are based on health standards and are known to be accurate.

How are calories calculated? Apple Watch calorie tracking is based on a scientific principle called the metabolic rate. Metabolic rate is how quickly the body expends the calories ingested through food intake. Each individual has a unique metabolic rate, but scientists can accurately predict an individual’s metabolic rate based on their age, gender, weight, and height.

When you set up your Apple Watch, you give Apple this information in the Health app. It then uses this personal information to calculate your Basal Metabolic Rate (BMR), which is your metabolic rate under normal resting conditions, and your Active Metabolic Rate (AMR), which is your metabolic rate while you are exercising. Apple Watch uses your heart rate and movement to detect increases or decreases in activity, which measures AMR.

The Apple Health app determines how much the average person of your size, age, and gender needs to exercise in order to run a calorie deficit. Meaning how much you need to move and be active to burn more than the number of calories you consume in a day. For more tips on using your Apple Watch for fitness, check out our free Tip of the Day newsletter.

How Does Apple Watch Calculate Calories Burned?

How to Improve Apple Watch Calories Burned Accuracy

Because calorie usage depends so much on your own biology, it's essential that your Apple Watch is updated with the latest information regarding your weight and height. This can be done in the Health app. This Health app information is also key to tracking your exercise minutes correctly when using your Apple Watch, so keeping it updated is a good habit to get into. If you've already done this, skip down to how to calibrate your Apple Watch. Finally, it is always best to select the most accurate workout from the list of activity options, I'll go over why selecting the right Apple Watch exercises makes a difference.

How to Update Your Height & Weight in the Health App

Open the Health app on your iPhone.
Tap Browse.
Tap Body Measurements.
If you've gained or lost weight, or grown taller, the number of calories you burn each day will change, so scroll down until you see Height or Weight and tap the category that needs to be updated.
Select Add Data, input your new height or weight, and tap Add.

If you don't want to manually update your weight (or other biometric information) manually, you can get a smart scale or devise and set it up to automatically update your Health app. My go-to is the Withings Body Comp scale ($199) that syncs every weigh in with the Health app via the Withings app (free). There are many smart scale options and price points, just make sure it' compatible with Apple Health before you make a purchase.

Withings Body Comp scale (99)

You will want to ensure that your watch is not too loose, since a poorly fitting watch band can interfere with Apple Watch heart rate accuracy. Also, ensure that when you exercise, you select the activity from the Workout app on your Apple Watch that most closely matches the exercise you are performing to allow Apple Watch to accurately track your movement.

Pro Tip

Keep in mind that tattooed skin may interfere with the accuracy of the heart rate sensors. If one of your wrists has tattoos where the Apple Watch's back sensors are, try wearing it on your other wrist to see if it makes a difference.

How to Calibrate Apple Watch

There are two things you need to know about calibrating your Apple Watch. If you have a new Apple Watch, it will give you instructions on how to record your first outdoor walk or run to make sure your future workouts are recorded as accurately as possible. Some refer to this as calibrating your Apple Watch. There is also a setting called Motion Calibration & Distance that should be toggled on for best Apple Watch results. To make sure this is toggled on or to enable it:

Open Settings on your iPhone.
Tap Privacy & Security.
Tap Location Services.
Scroll to the very bottom and tap System Services.
Make sure Motion Calibration & Distance is toggled on (green).

This should improve your workout and activity accuracy on your Apple Watch. Did you know that Apple Watch swimming tracking is pretty accurate in pools? Find out if your Apple Watch is waterproof because not all of them are.

How to Select An Apple Watch Exercise for Best Calories Burned Accuracy

We've discussed how the Apple Watch uses your heart rate and biometric data to calculate how many active vs total calories you burn throughout the day. While the Apple Watch is pretty good at detecting motion, it isn't able to perfectly detect what exact activity you are doing. When you select a workout type on your Apple Watch, you are helping the device figure out whether to use its internal walking calories calculator, treadmill calorie calculator, or running calorie calculator. Apple works hard to add new workout types and develop tools that can help you track things like the speed of your tennis serve. If the watch knows that you are playing tennis and not just jogging, it can better calculate how many calories you are burning using an algorithm based on existing data about the particular activity combined with your specific heart rate, biometric information, and time spent doing said activity.

The full list of available Apple Watch workouts can be accessed by scrolling to the very bottom of the Workout app on tapping Add Workout to see the full list. There is also a workout called "Other" that can be used if your desired workout isn't available. Keep in mind that "Other" will measure your workout as if you were going on a brisk walk. So while it might be a good idea to use while you deep clean your house or paint a room, it can be better to pick a workout that mimics the activity you are doing as closely as possible.

Select An Apple Watch Exercise

Now you know how Apple Watch calculates calories burned according to heart rate in addition to other factors, and how to improve the accuracy by changing a few settings and updating your Health app information. Plus, we covered what total calories vs active calories mean and how the Apple Watch calculates it. Although it isn't perfect, the Apple Watch fitness features are pretty impressive. Next, learn about Apple Watch Rings, Trends, and Challenges!

FAQ

Is Apple Watch heart rate accurate? Yes. Studies show that Apple Watch has pretty accurate heart rate readings, but it cannot replace medical equipment if you have any heart health concerns.
What is the difference between active and total calories? Active calories are those you burn on top of those burned while you breathe, rest, think, and even sleep. Total calories is your active calories plus the calories you burn just by existing.
Does Apple Watch have a walking calorie calculator or a running calorie calculator? Not exactly. The Apple Watch uses the biometric information that you enter in the Health app and your heart rate measurements to guesstimate how many calories you burn when you walk, run, or do other activities.
Is Apple Watch the most accurate fitness tracker? It is hard to determine which fitness tracker is the best, especially with so many models of Apple Watches (and other fitness trackers) out there. One of the more recent studies, published in 2022, the Apple Watch 6 was considered the most accurate for measuring heart rate when compared to the Fitbit Sense and Polar Vantage V. However, the results varied depending on the activity being tracked. No matter what fitness tracker you use, you should always take the energy expenditure with a grain of salt, especially if you have medical requirements or limitations.
How do I track steps on Apple Watch? Open the Activity app to see how many steps you've taken that day. You can also add a complication to show steps on your Apple Watch face.

Top image credit: Chinnapong / Shutterstock.com