The Apple Watch uses its heart rate sensor and motion sensors to estimate the number of calories you burn throughout the day and during workouts. However, the calorie burn calculations aren’t always accurate and you may notice your Apple Watch showing too many or too few calories burned.
Why is my Apple Watch calorie burn inaccurate?
There are a few reasons why the calorie burn on your Apple Watch may be inaccurate:
- Inaccurate heart rate data – The heart rate sensor can sometimes misread your heart rate, leading to incorrect calorie burn estimates.
- Inaccurate motion data – The motion sensors that track your movement can sometimes be off, also causing incorrect estimates.
- Inaccurate personal stats – If your height, weight, age etc are wrong in your profile, this will affect the calorie calculation.
- Activity miscategorization – The watch may incorrectly categorize some activities, like counting a walk as a run, affecting calorie burn.
How can I improve Apple Watch calorie accuracy?
Here are some tips to help get more accurate calorie burn from your Apple Watch:
1. Check and update your personal stats
Make sure your height, weight, age and other personal stats are correctly entered in the Health app on your iPhone. Inaccurate stats will lead to incorrect calorie burn. To update:
- Open the Health app on your iPhone.
- Tap your profile picture in the top right.
- Tap Edit and enter your details including height, weight and gender.
- Tap Done when complete.
2. Calibrate your Apple Watch
Calibrating your Apple Watch can help improve the accuracy of motion and heart rate data:
- Open the Apple Watch app on your iPhone.
- Go to My Watch > General > Calibrate.
- Follow the on-screen instructions to complete the calibration.
3. Tighten the watch on your wrist
If your Apple Watch is loose on your wrist, this can allow ambient light to affect the heart rate sensor accuracy. Try tightening your watch strap for a snugger fit that keeps the sensor in firm contact with your skin.
4. Wear your watch higher on your wrist
Wearing your Apple Watch higher up your wrist so it sits just above the wrist bone can also improve heart rate monitoring compared to wearing lower down the arm.
5. Use the Workout app
For dedicated workout sessions, start a workout in the Workout app on your watch. This will improve activity tracking and calorie accuracy compared to casual daily activity:
- Open the Workout app and select a workout type e.g. Run, Cycle.
- Start your workout. The watch will now use GPS and heart rate data.
- End the workout when complete and save it.
6. Analyze calorie accuracy over time
Look at your calorie burn trends over weeks and months to get a better sense of accuracy. Your weekly averages can help identify if your watch is consistently under or overestimating:
- Open the Health app and go to Activity > Calories.
- Review your daily and weekly calorie burn averages.
- Compare to your expected burn based on workouts.
7. Contact Apple Support
If none of the above tips fix persistent calorie inaccuracies, contact Apple Support. They can troubleshoot your watch specifically and may recommend service if a hardware issue is suspected.
How does the Apple Watch calculate calories?
The Apple Watch uses your heart rate data, motion data from the accelerometer, gender, age, height and weight to estimate calories burned. The exact formula Apple uses is proprietary, but in general:
- Active calories are calculated from heart rate elevated above resting.
- Resting calories are estimated based on stats like gender, weight and height.
- Motion sensing tracks steps, distance, flights climbed.
Apple’s algorithm then calculates total caloric expenditure based on all these signals. But as it is only an estimate, inaccuracies can occur due to bad sensor data or incorrect personal stats.
How accurate are calorie burn estimations?
No device can provide 100% accurate calorie burn measurements outside of a clinical setting. However, Apple Watch calorie accuracy is fairly reasonable when worn correctly. Here are some accuracy estimates:
- Active calorie accuracy is around 90-95% accurate during workouts.
- Daily calorie accuracy averages 80-90% for most wearers.
- Accuracy can vary significantly with incorrect personal stats.
Apple Watch calorie burn accuracy declines during casual daily wear compared to dedicated workout sessions. But overall it provides a good estimate of caloric expenditure for most users.
Should I eat back exercise calories burned?
Whether to eat back the calories your Apple Watch shows you burning during exercise depends on your goals:
- Weight loss – Don’t eat back exercise calories as Watch estimations can be inaccurate.
- Maintenance – May eat back 50% of calories to account for tracking errors.
- Muscle gain – Can eat back most calories burned during workouts.
Those trying to lose weight are better off ignoring the exercise calorie numbers. But if trying to maintain or gain, you have more leeway to eat some calories back without risk of overestimating.
How many calories does Apple Watch burn per hour?
Calories burned per hour on Apple Watch can vary significantly based on the type and intensity of activity. Here are rough estimates:
| Activity | Calories Burned Per Hour |
|---|---|
| Sitting | 50-100 |
| Light walking | 200-300 |
| Yoga | 300-400 |
| Running (10 min mile) | 700-800 |
| Hiking uphill | 700-900 |
| Cycling (moderate effort) | 400-600 |
The more intense the activity, the more calories will be burned per hour as heart rate increases. Always remember these are estimations and your actual burn may be higher or lower.
Does Apple Watch overestimate calories?
In some cases, yes Apple Watch can overestimate calories burned compared to your actual expenditure. Common reasons include:
- Inaccurate heart rate tracking during exercise.
- Mistaking casual activities like walking as more intense exercise.
- Inaccurate user stats like height, weight and age.
- Defective sensors providing incorrect motion data.
Issues like loose fit, incorrect personal details and categorization errors are common reasons for overestimation. Fortunately the tips provided earlier can help correct many overestimation issues.
Why do different exercises show different calorie burns?
The type of activity greatly impacts calories burned because different exercises work the body in different ways. Here are some factors that account for calorie differences between activities:
- Intensity – Higher intensity burns more calories as heart rate increases.
- Muscles used – Full body vs isolation exercises burn different amounts.
- Skill – Novice vs skilled athletes burn calories differently.
- Efficiency – How efficiently you can perform the movements.
This explains why something like running may burn far more calories than yoga for the same person. The impact on the muscles, skill required, intensity and mechanics of each exercise play a major role.
Does the Apple Watch measure calories for strength training?
Yes, the Apple Watch can estimate calories burned during strength and resistance exercises like weightlifting. It does this by tracking:
- Elevated heart rate to estimate effort exerted.
- Motion sensors to detect arm movements.
- Categorizing the activity as strength training.
However, calorie accuracy for strength training is lower than for cardio exercise. Additional factors like muscles targeted and weight used cannot be accounted for. But it still provides a reasonable estimate in most cases.
Can I improve HIIT workout calorie accuracy?
High intensity interval training (HIIT) workouts can be inaccurately tracked by Apple Watch due to rapid heart rate changes. To improve accuracy:
- Start a HIIT workout in the Workout app on your watch.
- Ensure your watch is snug on your wrist throughout the workout.
- Calibrate your watch if you haven’t done so recently.
- Consider a chest strap heart rate monitor for most accurate data.
Recording the workout properly in the Workout app and getting a tight fit will provide the best results. A chest strap can also help but isn’t required for reasonable accuracy.
Should I log indoor cycle classes as Indoor Cycle or Other?
For indoor cycling classes where your bike resistance is variable, it’s best to log as “Indoor Cycle” on Apple Watch. This will measure calories most accurately by combining heart rate and motion data.
If your spin bike doesn’t have adjustable resistance like Peloton, you can log as “Other” and let heart rate be the calorie driver. Just ensure your watch is fitting snugly.
Logging specific workout types where applicable leads to more accurate calorie burn estimates compared to the generic “Other” category.
Why do calories show 0 for strength training?
If your Apple Watch shows 0 calories burned for strength workouts occasionally, there are a few possible reasons:
- Loose fit – A loose watch can’t reliably track heart rate to estimate effort.
- Weak wrist motions – Smaller wrist motions may not be detected.
- Incorrectcategorization – The watch may incorrectly log it as a non-workout.
To avoid zero strength training calories, tighten your watch band and use larger range of motion exercises. Also manually start strength workouts in the Workout app when possible.
Conclusion
Accurately tracking calorie burn on Apple Watch requires a well-fitting watch worn consistently, properly categorized workouts, and correctly entered personal statistics. Periodically recalibrating the watch and analyzing long-term burn trends can also help optimize calorie accuracy. While estimations won’t be perfect, following the tips in this guide will maximize the Apple Watch’s ability to track your caloric expenditure.
