By Zencalcy Editorial TeamLast reviewed About us
This calculator estimates calories burned from your average heart rate during exercise. It uses the Keytel equations, which relate heart rate, body weight, age, and sex to energy expenditure. Enter the average heart rate for the session and the total minutes to see the estimate.
Estimate calories burned from your average exercise heart rate.
kcal/min (men) = (−55.0969 + 0.6309·HR + 0.1988·weight + 0.2017·age) / 4.184 kcal/min (women) = (−20.4022 + 0.4472·HR − 0.1263·weight + 0.074·age) / 4.184 kcal = kcal/min × minutes
The equation can return a small negative rate at very low heart rates, which is not physical. The result is floored at zero so the estimate never drops below no burn.
| Symbol | Meaning |
|---|---|
| HR | Your average heart rate during the workout, in beats per minute. |
| weight | Your body mass in kilograms. |
| age | Your age in years. |
| minutes | Total workout duration in minutes. |
For a 35 year old man weighing 80 kg with an average of 140 bpm, the men equation returns about 13.4 kcal per minute, so a 45 minute session burns roughly 604 kcal.
When you have a heart rate monitor but no laboratory testing, the Keytel equation estimates energy expenditure from heart rate, body weight, and age, with separate coefficients for men and women. For men the raw value is minus 55.0969 plus 0.6309 times heart rate plus 0.1988 times weight in kilograms plus 0.2017 times age.
For women the raw value is minus 20.4022 plus 0.4472 times heart rate minus 0.1263 times weight plus 0.074 times age. The raw result is in kilojoules per minute, so dividing by 4.184 converts it to kilocalories.
Heart rate rises with exercise intensity because your muscles demand more oxygen, so it is a convenient proxy for how hard the body is working. The equation captures the roughly linear relationship between heart rate and oxygen consumption across the moderate range of effort, which is why the estimate is most reliable between a light warm up and a hard but steady pace.
Accuracy falls apart at the extremes. Very low heart rates near resting are dominated by the large constant term, and very high rates sit outside the range where the linear fit holds. Caffeine, heat, stress, and medication can raise heart rate without raising calorie burn, so a fast pulse is not always a high energy cost.
Continue with the Elliptical Calorie Calculator, Fat Burning Zone Calculator, or the Hiking Calorie Calculator — or browse more calories burned tools and all sports calculators.
Use the average across the whole session, not your peak. A chest strap or a watch that records continuously gives a better average than a single reading.
Every result is computed locally in your browser from the formulas shown above. Nothing you type is uploaded, logged, or stored, and no account is required.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026