The total calories reading on the Apple Watch refers to the estimated number of calories you have burned throughout the day based on your activity. The Apple Watch uses data like your heart rate, movement, basal metabolic rate (BMR), and any logged workouts to calculate this estimate.
How does Apple Watch calculate total calories?
The Apple Watch uses a variety of sensors and input data to estimate your total calorie burn for the day. Here is an overview of how it calculates this number:
- Heart rate data from the optical heart rate sensor on the back of the watch. Your heart rate can indicate how many calories you are burning.
- Accelerometer data that detects motion and intensity of movement. More vigorous activity like walking briskly or running will burn more calories.
- Your basal metabolic rate (BMR). This is an estimate of how many calories you burn just to sustain basic bodily functions like breathing, circulating blood, etc. The watch uses your age, height, weight and gender to estimate BMR.
- Any calories logged during workouts you track on the watch like running, cycling, swimming, etc. The watch uses your heart rate, duration and movement to estimate calories burned.
- Your total step count for the day. Taking more steps burns more calories.
- Data from third-party apps that you allow to share workout data with the Apple Health app.
The Apple Watch combines all this data to make an educated estimate of how many total calories you have expended throughout the day. However, it is still an approximation and not 100% accurate.
What affects the total calorie number?
Several factors can influence the total calorie reading on your Apple Watch:
- Active vs inactive days: Days when you are more active with workouts, walking, running errands, etc. will show much higher calorie totals than sedentary days.
- Intensity of activity: Vigorous exercise like HIIT workouts will result in higher calorie burn than low-intensity activity like walking.
- Workouts: Logging activities like running or swimming provides more accurate data for the watch to use in its calculations.
- Accuracy of heart rate data: The optical HR sensor can sometimes be inaccurate, leading to over or under estimation of calorie burn.
- User inputs: Making sure your height, weight, age and gender are up to date will help improve BMR accuracy.
In general, being more active through the day, tracking workouts accurately, and ensuring user data is correct will yield the most accurate total calorie estimates.
Does total calories include basal metabolic rate?
Yes, the total calories number shown on Apple Watch does include your estimated basal metabolic rate (BMR) for the day in addition to your active calories.
Your BMR represents the minimum number of calories your body needs to perform essential functions like breathing, circulating blood, repairing cells, etc. This makes up the majority of the calories you burn each day.
So the total calories shown includes both:
- Your BMR calories
- Any active calories burned through movement, workouts, etc.
This provides a complete picture of your estimated calorie expenditure for the day.
Does the Watch know when I’m exercising?
The Apple Watch can automatically detect some types of exercise using its sensors, but it works best when you manually start a workout.
Here is what the watch can detect:
- Brisk walking and running: The accelerometer and heart rate sensor can recognize sustained faster movement characteristic of brisk walks and runs. You’ll get a notification asking if you want to log this as a workout.
- Swimming: The watch can use arm motions characteristic of swimming to auto-detect swim workouts when worn in water.
However, many types of exercise like biking, strength training, rowing, etc. cannot be auto-detected. For best results you should manually select the appropriate workout type on your watch at the start of the activity so it knows exactly what you are doing.
How to start a workout on Apple Watch
Here are the basic steps to start logging a workout on your Apple Watch:
- Open the Workout app on your watch.
- Scroll through and select the workout type you are about to start – for example, running, cycling, yoga, etc.
- Tap the red “Start” button at the bottom of the screen. Your watch will begin recording the workout.
- Once complete, tap “End” and “Save” to close out and save the workout data.
Logging the specific type of workout allows the watch to use the appropriate algorithms and heart rate data to calculate calories burned.
Does the Watch know my fitness level?
No, the Apple Watch does not automatically know your general fitness level or conditioning. However, there are a few things you can do to help it better estimate calorie burn:
- Enter your height, weight, age and gender accurately in the Health app. This helps with BMR estimates.
- Choose the correct workout type when logging activities. Choosing “Hiking” vs “Walking” will impact calorie algorithms.
- Set up heart rate zones in the Health app if you know your aerobic zones from fitness testing. This can help the watch interpret heart rate effort.
- Allow access to third party apps like TrainingPeaks or Final Surge. These apps use additional data like VO2max to estimate caloric expenditure.
While the watch doesn’t automatically know your fitness, taking the time to dial in these user-specific settings can help improve calorie accuracy.
Does Apple Watch count calories accurately?
The Apple Watch does a reasonable job of estimating calorie expenditure, but it is not 100% accurate. However, there are a few factors that impact its accuracy:
- The optical heart rate sensor can be off at times depending on fit, skin color, and type of activity. Inaccurate heart rate data will impact calorie accuracy.
- Calorie algorithms are based on general population estimates. The watch does not account for individual variations in efficiency.
- Calorie estimates are closest for brisk walking and running. Estimates are less accurate for activities like lifting weights or cycling.
That said, calorie estimates produced by the Apple Watch are generally in the ballpark when using the watch consistently and inputting accurate user data. While the total may not be perfect, the calorie tracking provides a useful indicator of your general activity levels and exertion.
Should I eat back exercise calories?
Whether or not to “eat back” the calories burned from exercise on the Apple Watch is a debated topic. Here are some things to consider:
- The calorie estimates are not perfect, so take them with a grain of salt.
- Eating back all your exercise calories can diminish the caloric deficit needed for weight loss.
- You do need to fuel appropriately for intense or long workouts to aid recovery.
A balanced approach is usually best. Consider eating back around half of the calories burned during high intensity workouts. And only eating back a quarter of calories from lighter exercise like walks. This ensures you are fueling adequately but still maintaining a calorie deficit.
How to ensure the most accurate calorie tracking
To get the most precise calorie burn estimates from your Apple Watch, keep these tips in mind:
- Log workouts manually – don’t rely on auto-detection
- Tighten your watch band during workouts for better heart rate
- Enter your physical stats like height, weight accurately
- Update your fitness profile and health data regularly
- Allow workout apps access through Apple Health
- Aim for at least 150 minutes of exercise per week for robust data
Calories burned through exercise is just one useful metric provided by the Apple Watch. Focus on long-term trends rather than daily numbers for the best insights into your fitness and health.
The bottom line
The total calories shown on your Apple Watch provides an estimate of your active calories burned plus resting metabolic rate throughout the day. This number is impacted by activity levels, workouts logged, health data entered, and the watch’s accuracy. While not 100% precise, it gives a helpful overview of your daily calorie expenditure when viewed over time.
| Pros | Cons |
|---|---|
| Gives an approximation of calorie burn | Not a perfect number |
| Influenced by workouts and activity | General algorithms may not match your body |
| Includes both active and BMR calories | Optical HR can be inaccurate at times |
At the end of the day, focus on trends over weeks and months rather than daily numbers for the best takeaways. Consider the Apple Watch total calories as a helpful metric, but not the end all be all measure for your health and fitness.
