Exercise Calorie Estimator
What Your Heart Rate Says About Calorie Burn
Activity-list calorie estimates (MET tables) assume a fixed intensity for a given activity, but two people jogging at the same pace can be working at very different relative efforts. Heart rate captures that difference directly. This calculator uses the Keytel et al. regression equations, which predict calorie burn rate from average heart rate, body weight, age, and sex — distinct, sex-specific formulas rather than a single one-size-fits-all curve.
The Formula
Two separate regression equations apply depending on sex:
Women: kcal/min = (−20.4022 + 0.4472×HR − 0.1263×Weight(kg) + 0.074×Age) ÷ 4.184
Weight entered in pounds is converted to kilograms first. The result is a calorie burn rate per minute, which is then multiplied by session duration to get total calories. If the regression produces a negative rate (possible at low heart rates relative to the other inputs), it is floored at zero rather than reported as negative.
Where This Calculation Matters
- Session-specific accuracy — because the formula uses actual average heart rate rather than an assumed activity intensity, it reflects how hard a specific session actually was, not just what activity it was labeled.
- Mixed-intensity workouts — interval sessions and circuit training don't map cleanly to a single MET value; average heart rate captures the blended intensity automatically.
- Cross-checking a heart rate monitor — comparing this calculation against a chest strap or watch's built-in calorie estimate, which often uses a similar heart-rate-based formula.
- Energy balance tracking — feeding a heart-rate-verified calorie figure into a daily energy balance calculation rather than an activity-label guess.
Sample Calculations
Applying the formulas to a 30-minute session at the same heart rate shows the sex-specific difference directly:
| Sex | Weight | Age | kcal/min | Total (30 min) |
|---|---|---|---|---|
| Male | 80 kg | 35 | 13.43 | 402.9 kcal |
| Female | 65 kg | 35 | 8.74 | 262.3 kcal |
These figures reflect the calculator's own regression formula at the stated inputs; use the calculator above for your own weight, age, and heart rate.
How to Use This Calculator
- Select the unit — Metric (kg) or Imperial (lb).
- Select Sex — Male or Female.
- Enter Age, Weight, Average Heart Rate during exercise, and session Duration in minutes.
- Select Calculate to see the calorie burn rate and total calories for the session.
Related Calculations
For an activity-list-based estimate that doesn't require a heart rate reading, see the Calorie Burn Calculator. To find the heart rate zone this session's average falls into, check the Heart Rate Zone Calculator.