How it's calculated
kcal = [(−55.0969 + 0.6309·HR + 0.1988·W + 0.2017·A) ÷ 4.184] × t
HR = heart rate (bpm), W = body weight (kg), A = age (yr), t = minutes. Keytel heart-rate equation (men shown; women use −20.4022 + 0.4472·HR − 0.1263·W + 0.0740·A). Max HR = 220 − age.
Common questions
Is heart rate a good way to estimate calories?
It is more personalized than MET tables for steady cardio, since it reflects how hard your body is actually working at the moment.
Why are the formulas different for men and women?
Body composition and oxygen use differ on average, so the Keytel study fit separate equations to improve accuracy for each.