BMR Calculator
Find your basal metabolic rate — the calories your body burns just to stay alive at rest.
How to use
- Pick your sex and enter age, height and weight.
- Your BMR is calculated with the Mifflin-St Jeor equation.
- Multiply BMR by an activity factor (see the TDEE tool) for daily needs.
How the BMR Calculator works
Estimates Basal Metabolic Rate — the energy your body uses at complete rest just to keep functioning. It is the foundation for any calorie target.
It uses the Mifflin-St Jeor equation, which is the most accurate of the common predictive formulas for the general population. Weight, height and age all contribute, with a constant that differs by sex.
men: 10W + 6.25H − 5A + 5 women: 10W + 6.25H − 5A − 161
(W in kg, H in cm, A in years)
Worked example
A 30-year-old man at 80 kg and 180 cm: 800 + 1,125 − 150 + 5 = 1,780 kcal a day at complete rest.
Things worth knowing
- BMR is not your daily calorie need. Multiply by an activity factor to get TDEE, which is what you would actually eat to maintain weight.
- Mifflin-St Jeor is a prediction from population averages. Individual metabolism varies by roughly ±10% around it.
- It does not account for body composition. At the same weight, more muscle means a higher true BMR than the formula predicts.
Frequently asked questions
What is BMR?
Basal metabolic rate is the energy your body uses at complete rest to keep vital functions running.
BMR vs TDEE?
BMR is rest-only; TDEE adds the calories you burn through daily activity and exercise.
Why does the formula differ by sex?
It is a proxy for average differences in body composition — men typically carry more lean mass, which burns more at rest.
Should I eat below my BMR to lose weight?
Generally not. Sustained intake below BMR is difficult to maintain and risks nutrient shortfalls; a moderate deficit from TDEE works better.