BMR Calculator
Calculate your basal metabolic rate (BMR), the calories your body burns at complete rest to keep its basic functions running. Further down, see how to get from BMR to a calorie target for weight loss.
How to use the BMR Calculator
- Enter your numbers in the BMR Calculator above.
- Press the Calculate BMR button to see the result.
- To try other numbers, change any value and press the button again.
The Mifflin–St Jeor BMR formula
Men: BMR = 10·W + 6.25·H − 5·A + 5 · · · Women: BMR = 10·W + 6.25·H − 5·A − 161
W is weight in kg, H is height in cm, A is age in years. Mifflin and colleagues published the equation in 1990 after measuring resting energy expenditure by indirect calorimetry in 498 healthy adults. In that group the Harris–Benedict equations from 1919 overestimated measured resting energy expenditure by 5%.
Worked example
A 30-year-old man weighing 80 kg at 180 cm: BMR = 10×80 + 6.25×180 − 5×30 + 5 = 800 + 1,125 − 150 + 5 = 1,780 kcal/day. A 40-year-old woman, 65 kg, 168 cm: 650 + 1,050 − 200 − 161 = 1,339 kcal/day.
How to use your BMR to lose weight
Your BMR is not the number to eat. It is what your body burns lying still for 24 hours, and you don't spend your days lying still. A weight-loss calorie target starts from total daily energy expenditure, or TDEE, which is BMR multiplied by an activity factor between 1.2 and 1.9.
Three steps get you from one to the other. Multiply the BMR from this page by your activity factor to get TDEE. Choose a deficit and subtract it. What is left is your daily intake target.
Take the man from the worked example, with a BMR of 1,780 kcal. Moderately active, at a factor of 1.55, his TDEE is 2,759 kcal. A 500 kcal deficit puts his target at 2,259 kcal a day, which is still 479 kcal above his BMR. Eating at his BMR would mean a deficit of 979 kcal a day, almost twice as large.
BMR moves as you lose weight because weight is an input to the equation. Each kilogram lost lowers the estimate by 10 kcal a day, so recalculate as your weight changes. The calculator can't tell you which deficit is right for your health. That is a question for a doctor or a registered dietitian.
These two calculators do the remaining steps:
Frequently asked questions
What's the difference between BMR and TDEE?
BMR is the calories you'd burn lying in bed all day. TDEE multiplies BMR by an activity factor (1.2–1.9) to capture daily movement, exercise and digestion. The TDEE calculator does that multiplication for you.
Is my BMR the number of calories I should eat to lose weight?
No. BMR is what you burn at rest, and a normal day burns more. The target comes from TDEE, which is BMR times an activity factor of 1.2 to 1.9, minus the deficit you choose. Even at the sedentary factor of 1.2, BMR is about 17% below TDEE. The calorie calculator works out TDEE and the reduced targets in one step.
Can I increase my BMR?
The estimate on this page moves only when an input does. It rises by 10 kcal a day for each kilogram of body weight and falls by 5 kcal for each year of age. In the 1990 study behind the equation, fat-free mass was the best single predictor of resting energy expenditure. Mifflin–St Jeor uses total weight, so it cannot tell muscle from fat.
Is the Mifflin–St Jeor formula universal?
No. It comes from 498 healthy adults aged 19 to 78, of whom 264 were normal weight and 234 obese, and it describes people like them best. It uses total body weight, so two people with the same weight, height, age and sex get the same BMR however much muscle they carry. The Katch–McArdle equation uses lean body mass instead of total weight.