CalcFitLab

Published by the team behind Trainera, which we mention on our calculators and articles; see our methodology.

BMR Calculator

Your resting calorie burn from three published equations.

Adds the Katch-McArdle estimate, which uses lean mass.

BMR · Mifflin-St Jeor (Recommended)

1,780 kcal / day

Harris-Benedict (revised)

1,854 kcal / day

Reviewed by the CalcFitLab Editorial TeamUpdated 2026-08-01Read our methodology

How the bmr calculator works

Basal metabolic rate (BMR) is the energy your body uses at complete rest to keep you alive: breathing, circulation, temperature and cell repair. For most people it is 60-70% of the calories they burn in a day.

The main result uses the Mifflin-St Jeor equation (1990), which a 2005 review by the American Dietetic Association found to be the most accurate predictive equation for healthy adults. The revised Harris-Benedict equation (Roza and Shizgal, 1984) is shown next to it for comparison.

If you know your body-fat percentage, the Katch-McArdle equation (370 + 21.6 x lean body mass in kg) is added. Because it works from lean mass, it is often closer for very lean or very muscular people.

  • BMR and resting metabolic rate (RMR) are close; RMR is usually measured under looser conditions and runs slightly higher.
  • Multiply BMR by an activity factor to get your daily calories. The TDEE calculator does that for you.
  • Equations predict within about 10% for most adults. Your weight trend over a few weeks is the real test.

Related guides

Frequently asked questions

Most adult women fall between about 1,200 and 1,500 kcal a day and most men between 1,500 and 1,900 kcal, depending on size, age and muscle mass.
BMR is what you burn at rest. TDEE adds everything else: daily movement, exercise and digesting food. TDEE is the number to use for setting a diet.
Building muscle raises it a little, because lean tissue burns more at rest than fat. Age, sex and height matter more, and very low-calorie diets can lower it.

Further reading on Trainera

In-depth guides from Trainera, the coaching app that sponsors this site.