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BMR Calculator
Work out your basal metabolic rate with the Mifflin-St Jeor equation, plus Katch-McArdle if you know your body fat.
Basal metabolic rate
Mifflin-St Jeor: —
Katch-McArdle: —
Lean body mass: —
How to use the BMR Calculator
- Enter your sex, age, height and weight.
- Optionally add your body fat percentage for Katch-McArdle.
- Read your basal metabolic rate in calories per day.
Features
- Mifflin-St Jeor equation
- Katch-McArdle from body fat
- Lean body mass shown alongside
- Runs locally, no uploads
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Frequently Asked Questions
Common questions about the free online bmr calculator.
The tool uses the Mifflin-St Jeor equation from your sex, age, height and weight, which is
the most accurate general purpose formula.
BMR is the energy you use at complete rest, while TDEE adds the calories burned through daily
activity and exercise on top of it.
It works out resting energy from lean body mass instead of total weight, so it needs your
body fat percentage and suits lean people.
Men usually carry more muscle and less fat at the same weight, so the equation uses a
different constant for each sex.
No. The Mifflin-St Jeor result appears without it, and the Katch-McArdle figure fills in only
once you enter a body fat value.
Yes. Resting energy use falls slowly with age, and the formula subtracts five calories for
every year of age to reflect that.
BMR is not a meal plan. It covers basic body functions only, and most adults need more than
this once daily activity is added.
No. It is an estimate for general information and not medical advice, so ask a doctor or
dietitian before making changes.
The calculator takes centimetres and kilograms. Divide pounds by 2.2 for kilograms and
multiply inches by 2.54 for centimetres.
Last updated: October 10, 2026