Per minute
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Calories Burned by Heart Rate
Estimate calories burned during cardio exercise using the Keytel heart-rate formula. More accurate than generic "METs" calculators for steady-state cardio because it uses your actual heart rate during the activity.
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calories burned
Equivalent walking
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Walking equivalent assumes a 70 kg person at 3 mph burns about 4 kcal/min. Use this to compare sessions.
How the Keytel formula works
For men: (-55.0969 + 0.6309 × HR + 0.1988 × weight + 0.2017 × age) / 4.184 × duration. For women: (-20.4022 + 0.4472 × HR - 0.1263 × weight + 0.074 × age) / 4.184 × duration. Output is total kcal. The formula is calibrated for healthy adults during steady-state cardio, so HIIT or weight training will be less accurate.
How this calculator works
Heart rate is a proxy for oxygen consumption, which in turn is a proxy for calorie burn. The Keytel formula (published 2001 in Journal of Sports Sciences) takes your sex, age, weight, average heart rate during the activity, and duration, and produces an estimate in kcal. The denominator 4.184 converts from kJ to kcal.
Frequently asked questions
Which heart rate formula is most accurate?
The Keytel formula (2001) used here is one of the more accurate published equations for healthy adults doing steady-state cardio. It uses sex, age, weight, heart rate, and duration. It is less accurate for HIIT, very high-intensity intervals, or people with heart-rate conditions.
Does a higher heart rate always mean more calories burned?
Mostly yes, but the relationship is not linear. Going from 120 to 140 bpm roughly doubles calorie burn, but going from 160 to 180 bpm adds only another 30-40%. The relationship flattens at very high heart rates because the body can no longer use all the oxygen being delivered.
How accurate are these calorie estimates?
Typically within 10-20% of measured values for steady-state cardio in healthy adults. Accuracy drops for interval training, resistance exercise, and people who are not average body composition. Treat the result as a planning estimate, not a precise measurement.
Last updated — formula based on Keytel 2001; typical accuracy ±15% for steady-state cardio in healthy adults.
Estimates for general wellness information, not medical advice — see our disclaimer.