About the Calories Burned by Heart Rate Calculator
This calculator estimates how many calories you burned during a workout from your average heart rate, the session length, and your age, weight and sex. It uses the Keytel equations (Journal of Sports Sciences, 2005), the most widely used published heart-rate calorie formulas, and can include your VO2 max for a more personalised estimate.
Heart rate captures how hard you actually worked, so it adapts to any activity — running, cycling, rowing, a spin class or circuit training — where a generic MET table can only guess. It is handy for logging workouts from a chest strap or watch that shows average heart rate but not calories, or for checking whether a device’s calorie count is plausible.
The equations were developed from 115 regularly exercising adults aged 18–45 during steady treadmill and cycling exercise at about 57–90% of maximum heart rate. They are least reliable at very low heart rates (sitting or strolling), during short all-out efforts, and for anyone whose heart rate is affected by medication, heat or stress.
With the default inputs, the calories burned is 594 kcal. Change any value above to recalculate instantly.
How to use the calories burned by heart rate calculator
- 1Choose your sex and enter your age and weight.
- 2Enter the average heart rate from your watch or chest strap for the workout.
- 3Enter how many minutes the workout lasted.
- 4Optionally add your VO2 max for a fitness-adjusted estimate.
- 5Read total calories, and use the table to compare heart rates.
Formula and method
Keytel and colleagues (Journal of Sports Sciences, 2005) measured oxygen uptake and heart rate in 115 adults and fitted separate equations for men and women. Each predicts energy expenditure in kilojoules per minute from heart rate (HR, bpm), body weight (W, kg) and age (A, years); dividing by 4.184 converts to kilocalories, and multiplying by duration gives the session total.
When you enter VO2 max, the fitness-adjusted equations are used instead — men: −95.7735 + 0.634·HR + 0.404·VO2max + 0.394·W + 0.271·A; women: −59.3954 + 0.45·HR + 0.380·VO2max + 0.103·W + 0.274·A. In the original study these explained about 83% of the variation in measured energy expenditure, versus about 73% for the equations without VO2 max.
- HR
- Average heart rate during exercise (bpm)
- W
- Body weight (kg)
- A
- Age (years)
- VO2max
- Maximal oxygen uptake (ml/kg/min), optional
Worked examples
35-year-old man, 75 kg, 140 bpm for 45 minutes
−55.0969 + 0.6309 × 140 + 0.1988 × 75 + 0.2017 × 35 = 55.20 kJ/min, or 13.19 kcal/min after dividing by 4.184. Over 45 minutes that is about 594 kcal.
42-year-old woman, 140 lb, 150 bpm for 60 minutes
140 lb is 63.5 kg. −20.4022 + 0.4472 × 150 − 0.1263 × 63.5 + 0.074 × 42 = 41.77 kJ/min = 9.98 kcal/min, so an hour at 150 bpm burns about 599 kcal.
Same man with a known VO2 max of 50
With VO2 max included: −95.7735 + 0.634 × 140 + 0.404 × 50 + 0.394 × 75 + 0.271 × 35 = 52.22 kJ/min = 12.48 kcal/min, or about 562 kcal in 45 minutes. That is about 32 kcal less than the estimate without VO2 max; how far the two versions differ depends on how your fitness compares with the study group.
Frequently asked questions
How accurate is calorie burn from heart rate?+
In the original Keytel study, the equations explained about 73% of the variation in measured calories without VO2 max and about 83% with it. Individual errors of 10–20% are common, especially at low heart rates or during interval workouts.
Why do men and women have different formulas?+
At the same heart rate, men on average have larger hearts and more muscle mass, so they move more oxygen per beat and burn more energy. Keytel’s team found that fitting separate equations by sex predicted calorie burn much better than a single equation.
Does a higher heart rate always mean more calories?+
For steady aerobic exercise, yes — calories rise roughly in line with heart rate. But heart rate also rises with heat, dehydration, caffeine and stress, which does not add calories, so hot-weather workouts may be overestimated.
Should I eat back the calories I burn?+
If you are training for performance, refuelling helps recovery. If you are trying to lose weight, many people eat back only part of the estimate, because exercise calorie figures from watches and formulas tend to err on the high side.
Can I use this for weightlifting?+
Only roughly. Strength training raises heart rate partly through straining and short bursts rather than steady oxygen use, so heart-rate formulas tend to overestimate calories for lifting. A MET-based estimate may be more realistic.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.