BMR calculator
Work out how many calories your body burns at complete rest, just to keep its vital functions going.
BMR calculator: what it is and how it works
Basal metabolic rate (BMR) is the energy your body needs at complete rest to keep vital functions running: breathing, pumping blood, regulating temperature and renewing cells. It makes up 60–70 % of a sedentary person’s daily calorie burn.
This calculator uses two equations. Mifflin-St Jeor (1990) is recommended by many dietetic associations for its accuracy in today’s population. The revised Harris-Benedict equation (1984) is the classic one. Both depend on sex, age, weight and height. To find your total daily calories, multiply the result by your activity level or use the calorie calculator.
How to use it
- Choose your sex.
- Enter your age, weight and height.
- See your BMR with both equations.
Mifflin-St Jeor: 10 × weight + 6.25 × height − 5 × age + 5 (men) or − 161 (women)Worked example
A 30-year-old man weighing 70 kg and 175 cm tall has a BMR of 1,649 kcal with Mifflin-St Jeor and 1,696 kcal with Harris-Benedict.
Frequently asked questions
Which equation is more accurate?
Comparative studies tend to favour Mifflin-St Jeor for adults of normal weight or overweight, although both have an error margin of about 10 %.
Can I increase my BMR?
Building muscle raises it slightly, because muscle uses more energy than fat at rest.
Why does BMR fall with age?
Mainly because of muscle loss and hormonal changes.
Should I eat only my BMR calories?
No. It is the minimum at rest; your real expenditure includes activity and digestion, and eating below it for long periods is not advisable.