BMR Calculator
Estimate basal metabolic rate — the calories your body burns at rest — using the Mifflin–St Jeor equation.
How to use this calculator
- Select biological sex (the published equation has sex-specific constants).
- Enter weight, height, and age in either unit system.
- The result is an estimate of resting energy expenditure in kcal/day.
The formula
Men: BMR = 10·kg + 6.25·cm − 5·age + 5 Women: BMR = 10·kg + 6.25·cm − 5·age − 161- kg
- Weight in kilograms
- cm
- Height in centimeters
- age
- Age in years
How it works
Basal metabolic rate is the energy your body needs for essential functions — breathing, circulation, cell repair — before any movement.
The Mifflin–St Jeor equation (1990) is the formula most often recommended by the Academy of Nutrition and Dietetics for estimating resting metabolism in healthy adults, and was shown to predict measured values within about 10% for most people.
Worked example
A 30-year-old man, 70 kg and 175 cm.
- 110 × 70 = 700
- 26.25 × 175 = 1,093.75
- 35 × 30 = 150
- 4700 + 1,093.75 − 150 + 5 = 1,648.75
BMR ≈ 1,649 kcal/day at complete rest.
When this calculator is useful
- A baseline for calorie planning
- Understanding how age, weight, and height affect metabolism
- Input for TDEE (total daily energy expenditure) estimates
Frequently asked questions
What is the difference between BMR and TDEE?
BMR is resting burn only. TDEE multiplies BMR by an activity factor to estimate everything you burn in a day.
Which BMR formula is best?
For most healthy adults, reviews have found Mifflin–St Jeor the most accurate of the common predictive equations, which is why this calculator uses it.