BMR Calculator

Your Basal Metabolic Rate (BMR) is the number of calories your body needs just to stay alive at complete rest — breathing, circulation, cell repair — before any activity is added. It's the starting point for most calorie and nutrition planning.

BMR Calculator

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Sex

Age

Height (cm)

Weight (kg)

Your BMR

1,780 cal/day

This is calories at total rest — see our TDEE Calculator to add your activity level.

The Mifflin-St Jeor formula

Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

Example

A 30-year-old man, 80 kg, 180 cm: BMR = 10(80) + 6.25(180) − 5(30) + 5 = 1,780 calories/day at complete rest.

Step-by-step guide

Select your sex — the formula uses a different constant for men and women.
Enter your age, height, and weight.
Read your BMR — this is your resting energy use, not your total daily calories. For that, add an activity level using our TDEE Calculator.

Common mistakes

Treating BMR as your total daily calorie needs — BMR excludes any activity, walking, or exercise entirely.

Using an older formula like Harris-Benedict without realizing Mifflin-St Jeor is generally considered more accurate for most modern populations.

Frequently asked questions

What's the difference between BMR and TDEE?

BMR is calories at complete rest. TDEE (Total Daily Energy Expenditure) adds your activity level on top of BMR, giving a more realistic estimate of daily calorie needs.

How accurate is this formula?

Mifflin-St Jeor is one of the more accurate population-level equations available, but any formula is an estimate — individual metabolism varies due to genetics, muscle mass, and other factors that a simple formula can't capture.

Does muscle mass affect BMR?

Yes — muscle tissue burns more calories at rest than fat tissue, so two people with the same height, weight, and age can have somewhat different actual BMRs depending on body composition.

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