BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest, just to stay alive: to breathe, pump blood, keep your brain working and hold your body temperature. For most people it is the largest part of the calories they burn in a day.
This calculator uses the Mifflin-St Jeor equation, which reviews have found to be the most accurate of the common formulas for healthy adults, and also shows the result from the older Harris-Benedict equation for comparison.
How to use the BMR calculator
- Choose your gender.
- Enter your age, weight (kg) and height (cm).
You will see your BMR from both formulas and the calories you need in a day if you mostly sit. Open the table below the result to see your daily calories at every activity level.
BMR formulas
Mifflin-St Jeor (1990)
Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161Harris-Benedict (revised in 1984)
Men: BMR = 88.362 + 13.397 × weight + 4.799 × height − 5.677 × age
Women: BMR = 447.593 + 9.247 × weight + 3.098 × height − 4.330 × ageExample
A 30-year-old man who weighs 70 kg and is 170 cm tall:
- Mifflin-St Jeor: 10 × 70 + 6.25 × 170 − 5 × 30 + 5 = 1,618 kcal a day
- Harris-Benedict: 1,672 kcal a day
His daily calorie needs by activity level (BMR × factor):
| Activity level | Calories a day |
|---|---|
| Sedentary (× 1.2) | 1,941 |
| Lightly active (× 1.375) | 2,224 |
| Moderately active (× 1.55) | 2,507 |
| Very active (× 1.725) | 2,790 |
| Extra active (× 1.9) | 3,073 |
For a 28-year-old woman who weighs 60 kg and is 160 cm tall, the Mifflin-St Jeor BMR is 600 + 1,000 − 140 − 161 = 1,299 kcal a day.
What changes your BMR
- Muscle: muscle burns more energy than fat, even at rest. Strength training helps keep your BMR up.
- Body size: taller and heavier people burn more.
- Age: BMR slowly falls with age, mostly because people lose muscle.
- Sex: men usually have a higher BMR because they carry more muscle.
- Health: thyroid problems, illness and some medicines can raise or lower BMR.
FAQ
Should I eat only as many calories as my BMR?
No. Your BMR is what you burn lying still all day. You also burn energy walking, working and digesting food, so you need more than your BMR. To plan your meals, use the calorie calculator, which adds your activity level and goal.
What is a normal BMR?
It depends on your size, age and sex. Many adult women fall somewhere around 1,200 to 1,500 kcal a day and many men around 1,500 to 1,900 kcal, but bigger and more muscular people can be higher.
Which BMR formula is more accurate?
For most healthy adults, Mifflin-St Jeor comes closer to measured values than Harris-Benedict, which tends to give slightly higher numbers. Both can be off by about 10% for an individual.
Does BMR go down with age?
Yes, slowly. A big reason is loss of muscle, so regular strength training and enough protein help slow the fall.
How can I increase my BMR?
Build muscle with strength training, stay active through the day, sleep well and avoid very low-calorie diets, which can make your body burn less.