How to use the BMR calculator
Choose metric or US units, then enter your sex, age, height and weight. If you know your body fat percentage, add it to see the Katch–McArdle result as well. The calculator shows your BMR by each formula and how many calories you burn in a day at different activity levels.
What is BMR?
Basal metabolic rate is the energy your body needs to stay alive at complete rest: breathing, circulating blood, keeping warm and repairing cells. It usually makes up 60% to 70% of the calories you burn each day. Activity, exercise and digesting food account for the rest.
The three formulas
- Mifflin–St Jeor (1990):
10 × kg + 6.25 × cm − 5 × age + 5for men,− 161for women. It is considered the most accurate for most adults. - Revised Harris–Benedict (1984): an update of the original 1919 equation, still widely used.
- Katch–McArdle:
370 + 21.6 × lean body mass in kg. It is based on lean mass, so it can be more accurate for very muscular or very lean people.
From BMR to daily calories
Multiplying BMR by an activity factor gives your total daily energy expenditure, the calories that keep your weight stable. Use the calorie calculator to turn that into targets for losing or gaining weight.
Frequently asked questions
What is a normal BMR?
For adults it is often between about 1,200 and 2,000 calories a day, depending mainly on size, age, sex and muscle mass.
Can I raise my BMR?
Building muscle through strength training raises BMR modestly, because muscle uses more energy at rest than fat.