BMR Calculator
Free to use. Runs in your browser: your files and text are not uploaded.
This tool gives general information only. It is not medical advice.
Enter your age, sex, height and weight to estimate the calories your body uses each day at rest.
How to use it
- Choose your sex and type your age.
- Choose metric or US units, then type your height and weight.
- Read your BMR, and your daily calorie use at each activity level.
The formula
The Mifflin-St Jeor equation:
- 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 woman, 165 cm and 60 kg. BMR = 10 × 60 + 6.25 × 165 − 5 × 30 − 161 = 600 + 1,031.25 − 150 − 161 = 1,320 calories a day.
What changes BMR
- Body size: larger bodies use more energy.
- Muscle: muscle uses more energy at rest than fat does. This is the main reason men’s figures are higher on average.
- Age: BMR falls with age, largely because muscle is lost.
From BMR to daily calories
Multiply BMR by an activity factor to estimate the calories used in a normal day: 1.2 for little or no exercise, up to 1.9 for very hard exercise or a physical job. The tool shows all five. For weight-loss and weight-gain figures, use the Calorie Calculator.
Limits
- This is an estimate from an equation. Measuring BMR directly needs laboratory equipment that analyses the air you breathe.
- For most healthy adults the equation is within about 10% of the measured value. It is less accurate for very muscular people and for people with obesity.
- It is not designed for children, or for pregnancy.
Frequently asked questions
What is BMR?
Basal metabolic rate is the energy your body uses in a day at complete rest, to keep you breathing, your heart beating and your body warm. It is usually the largest part of the calories you burn.
What is the difference between BMR and TDEE?
BMR is energy used at rest. TDEE, total daily energy expenditure, adds the energy used in movement and digestion. The lines under your BMR show TDEE at five activity levels.
Which BMR formula is used?
The Mifflin-St Jeor equation, published in 1990. A review by the American Dietetic Association in 2005 found it the most reliable of the common equations for healthy adults.