# Estimating How Many Calories Your Body Burns Per Minute of Exercise

Many calculators that estimate the calories burned during exercise do so by asking you what type of exercise you did (for example, running), and for how long (for example, 30 minutes). But these estimates aren’t very accurate because they don’t factor in your personal attributes, like weight and age. Luckily, researchers have known for a while that our bodies burn between 4.7 and 5 calories for every liter of oxygen consumed during exercise (source). Using this fact, it’s possible to develop a simple equation that uses three inputs—your weight, age, and the heart rate sustained during the exercise—to more accurately estimate how many calories you burn per minute of exercise (I call this the per-minute “aerobic caloric burn” (ACB)). Try it out for yourself with the calculator below—input your own values into the **green** cells.

## Limitations

The formula this calculator is based on comes from the study reported in Keytel, L.R. et al., “Prediction of energy expenditure from heart rate monitoring during submaximal exercise,” Journal of Sports Science, Volume 23 (2005), pgs. 289–297. The authors note that their formula (which is the one used in the calculator above) accounts for “73.4% of the variance in energy expenditure,” so the formula isn’t perfect. Moreover, the heart rates of the participants in the study ranged between 100 bpm and 180 bpm, so the results of the calculator shouldn’t be trusted to estimate ACB outside that heart rate

range.