Exercise Calorie Calculator
Standard calorie burn calculators assign a fixed energy cost to each activity type based on population-average metabolic equivalents. But your heart rate during exercise is a direct, real-time measure of your cardiovascular effort and oxygen consumption. This calculator uses the heart-rate-based regression equations developed by Keytel et al. (2005), which estimate calories burned from your average exercise heart rate, body weight, age, and sex. Because it uses your actual physiological response rather than an assumed activity intensity, the result is more personalised and more accurate for sustained aerobic activities such as running, cycling, rowing, or swimming. Enter the average heart rate you maintained throughout your session (not your peak), your body weight in kilograms, your age, your biological sex, and the session duration in minutes. The formula produces separate results for male and female physiology. It is validated for heart rates between approximately 90 and 180 bpm during aerobic exercise and is less accurate at very low intensities or during stop-start anaerobic activity.
Formula
Male: Calories/min = (-55.0969 + 0.6309*HR + 0.1988*weight + 0.2017*age) / 4.184
Female: Calories/min = (-20.4022 + 0.4472*HR - 0.1263*weight + 0.074*age) / 4.184
Total calories = Calories/min * duration (minutes)
HR = average heart rate in bpm, weight in kg
(Keytel LR, et al., 2005)
Exercise Calorie Calculator: frequently asked questions
How does heart rate predict calories burned?
Heart rate correlates closely with oxygen consumption, which in turn determines calorie burn. During aerobic exercise, as intensity increases, heart rate and oxygen uptake rise together in a predictable relationship. The Keytel formula uses this relationship, combined with body weight and age, to estimate calorie expenditure more accurately than MET-based methods for sustained aerobic activity.
How is this different from the MET-based calorie calculator?
MET-based calculations assign a fixed energy cost to each activity type regardless of individual intensity. The heart-rate method measures your actual physiological response to exercise. Two people running at the same pace may have very different heart rates and thus different calorie burns. The heart-rate method captures this individual variation better, provided you use your actual average heart rate during the session.
Which heart rate should I enter?
Enter your average heart rate during the exercise session, not your peak or ending heart rate. Many fitness trackers and heart rate monitors provide an average HR for a workout. If you are estimating, use a value that reflects your typical effort during the session. The formula is least accurate for very short bursts (under 10 minutes) or for highly intermittent exercise like HIIT.
Are the male and female formulas different?
Yes. The Keytel et al. (2005) study derived separate regression equations for men and women. The male formula uses coefficients that reflect the typically higher muscle mass and oxygen efficiency of male physiology. The female formula uses different coefficients that are validated for the female population studied. Using the wrong formula adds systematic error.
How accurate is this calorie estimate?
The Keytel formula has a standard error of approximately 10 to 15% for most adults during sustained aerobic exercise at 60 to 90% of maximum heart rate. It is less accurate below 60% intensity (low heart rates) and during anaerobic exercise where the heart rate-VO2 relationship is less linear. For most practical purposes it is as good as or better than tracker devices that use similar methods.
Official sources
- Keytel LR, et al. (2005). "Prediction of energy expenditure from heart rate monitoring during submaximal exercise." Journal of Sports Sciences, 23(3):289-297.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.