BMR Calculator
Basal metabolic rate counts the calories your body spends doing nothing: breathing, pumping blood, repairing tissue, keeping warm. For most adults it is 60–70% of the daily total, which makes it the anchor for any diet or training plan. This page works the figure out with the Mifflin-St Jeor equation, the formula nutrition researchers currently prefer, and shows every step of the arithmetic.
Enter values
Results
- Basal metabolic rate
- 1,593 kcal/day
- What that figure covers
- 24 hours of complete rest
- Equation used
- Mifflin-St Jeor (1990)
How is the BMR calculated?
Enter four things: weight in kilograms, height in centimetres, age in whole years, and sex — the equation's constant differs by 166 kcal between men and women. Weight is multiplied by 10, height by 6.25 and age by 5, then the sex-specific constant is added. What comes back is a resting figure for 24 hours, with no allowance yet for walking, working or training.
Formula
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age(years) + s, where s = 5 for men and s = −161 for women. Weight is body mass in kilograms, height is stature in centimetres, age is in years. Mifflin and colleagues published the equation in 1990; it beat the older Harris-Benedict formula in validation studies and is now the standard estimate.
Example
A 35-year-old man weighing 70 kg at 170 cm: 10 × 70 = 700, 6.25 × 170 = 1,062.5 and 5 × 35 = 175, so 700 + 1,062.5 − 175 + 5 = 1,592.5 kcal a day. The identical body as a woman gives 700 + 1,062.5 − 175 − 161 = 1,426.5 kcal. Both describe a day spent entirely at rest: a seated week multiplies this by about 1.2, and training five days a week by roughly 1.55.
Things to remember
Treat basal burn as a floor rather than a target — eating only this much leaves nothing for commuting, training or fighting off a cold. Re-run the sum after a shift of 5 kg or more, and remember the answer predicts a population average rather than your own metabolism.
Frequently Asked Questions
How do I calculate my BMR by hand?
Multiply weight in kg by 10, height in cm by 6.25 and age by 5, add them, then add 5 for men or subtract 161 for women. The 70 kg, 170 cm, 35-year-old example above lands on 1,592.5 kcal before any activity is counted.
What is the difference between BMR and TDEE?
Basal burn covers a body lying still for 24 hours, while total daily expenditure adds movement, digestion and training on top. The same 1,593 kcal resting figure becomes 1,911 kcal on a desk-bound day or 2,468 kcal when exercise is regular.
Why does my metabolic rate drop with age?
The equation deducts 5 kcal for every extra year because adults shed lean tissue as they age, typically 1–2% a decade after thirty without training. Lifting weights and eating adequate protein are the practical ways to soften the decline the formula assumes.
Should I eat only my BMR calories to lose weight?
Usually not — dropping to basal burn leaves no fuel for daily life, so sensible plans start nearer maintenance minus 500 kcal. Read the BMR row as the number you stay above, then let the TDEE result set the actual eating target you follow.
Related Calculators
- TDEE CalculatorHealth & FitnessEstimate your total daily energy expenditure to see how many calories you burn each day at your activity level.
- BMI CalculatorHealth & FitnessCalculate your Body Mass Index from height and weight and see which category you fall into.
- Macro CalculatorHealth & FitnessSplit your daily calories into protein, carbohydrate and fat grams for a cutting, maintenance or bulking goal.
- Age CalculatorDate & AgeCalculate your exact age in years, months and days plus total days and hours lived from your date of birth.