How it works
First the tool estimates your basal metabolic rate (BMR), the energy your body uses at rest, with the Mifflin-St Jeor equation (1990):
- Men: 10 x weight (kg) + 6.25 x height (cm) - 5 x age + 5
- Women: 10 x weight (kg) + 6.25 x height (cm) - 5 x age - 161
Then it multiplies BMR by an activity factor, from 1.2 for a desk job with no exercise to 1.9 for a physical job plus hard training. The result is your total daily energy expenditure (TDEE).
How accurate is it?
Mifflin-St Jeor is one of the more reliable equations for adults, but any formula can be off by a few hundred calories for a given person. Treat the number as a starting point and adjust after two or three weeks of tracking your weight.
