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BMR Calculator

Your basal metabolic rate (BMR) is the number of calories your body burns at complete rest just to keep you alive. Enter your details to estimate it with the well-validated Mifflin-St Jeor equation.

About you

Basal metabolic rate
1,780

calories burned at rest per day (Mifflin-St Jeor)

  • Harris-Benedict estimate
  • Calories/day if sedentary (×1.2)
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How it works

The Mifflin-St Jeor equation estimates BMR from weight, height, age and sex:

BMR = 10·weight(kg) + 6.25·height(cm) − 5·age + s

where s = +5 for men and s = −161 for women. To get the calories you actually burn in a day, multiply BMR by an activity factor (1.2 sedentary up to 1.9 very active) — that's your TDEE.

Worked example

A 30-year-old man, 180 cm, 80 kg:

Frequently asked questions

What is the difference between BMR and TDEE?
BMR is the calories you'd burn lying in bed all day — the energy for breathing, circulation and basic cell function. TDEE (Total Daily Energy Expenditure) is BMR plus the calories you burn moving around, so it's always higher. To estimate TDEE, multiply BMR by an activity factor.
Which BMR equation is most accurate?
The Mifflin-St Jeor equation is generally considered the most accurate for the general population and is what this calculator uses. The older Harris-Benedict equation (shown for comparison) tends to read slightly higher.
Why does BMR fall with age?
Resting metabolism declines gradually with age, largely because people tend to lose muscle mass over time. Muscle burns more energy at rest than fat, so keeping muscle through resistance training helps maintain a higher BMR.

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