BMR calculator
The calories your body uses at complete rest, before you move at all.
The formula, in full
Mifflin St Jeor, 1990, in metric units:
- Men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
- Women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
Worked through for the default values above: (10 × 70) + (6.25 × 170) − (5 × 30) + 5 = 700 + 1062.5 − 150 + 5 = 1618 kcal.
Where it came from, what the 1990 study measured and how well it has held up are inthe Mifflin St Jeor equation, explained.
What it leaves out
The equation knows your weight, height, age and sex, and nothing else. It does not know how much of your weight is muscle, and muscle burns more at rest than fat does, so two people of identical size and different build will have genuinely different resting rates and the same predicted one.
If you know your body fat: Katch McArdle
Add a body fat figure above and a second line appears under your result, worked from your lean mass instead of your weight. Cunningham's 1980 reanalysis of the original Harris and Benedict data found lean body mass was the single predictor of resting rate, with sex and age adding little once it was known. Katch McArdle works the same way.
BMR = 370 + 21.6 × lean mass in kg
It can only be as good as the body fat figure you give it. A number from a tape measure or a scan is worth using. One estimated from your BMI tells it nothing Mifflin St Jeor did not already know, so leave the box empty. The TDEE and calorie deficit calculators stay on Mifflin St Jeor either way.
To turn this into something you can eat to, use theTDEE calculator.
Common questions
What is BMR?
Basal metabolic rate is the energy your body uses keeping you alive at complete rest: breathing, circulation, brain, organ function, maintaining temperature. For most people it is 60 to 70 percent of everything they burn in a day.
What is the Mifflin St Jeor formula?
For men, 10 times weight in kilograms plus 6.25 times height in centimetres minus 5 times age in years plus 5. For women the same, but minus 161 at the end instead of plus 5. It was published in 1990 and has held up better than the older Harris Benedict equation in validation studies.
Is BMR the same as TDEE?
No. BMR is rest only. TDEE is BMR plus everything else you do: moving, exercising, digesting. TDEE is the number you would actually eat to, and it is BMR multiplied by an activity factor. The TDEE calculator does that step.
Should I eat at my BMR?
No. BMR is what you burn doing nothing, so eating at it means a substantial deficit once you stand up. Very low intakes are not something to aim at without medical supervision. Use TDEE for a target.
Why is my BMR different in another calculator?
Different equations. Harris Benedict, Mifflin St Jeor, Katch McArdle and Cunningham all exist and all give different numbers for the same person, and Katch McArdle needs a body fat figure. None is exactly right for an individual, because actual resting metabolism varies between people of identical size.
Sources
Every figure above comes from one of these. Check them.
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO (1990). A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition 51(2)
- Frankenfield D, Roth-Yousey L, Compher C (2005). Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults. Journal of the American Dietetic Association 105(5)
- Cunningham JJ (1980). A reanalysis of the factors influencing basal metabolic rate in normal adults. American Journal of Clinical Nutrition 33(11), 2372-2374
- McArdle WD, Katch FI, Katch VL. Exercise Physiology: Nutrition, Energy, and Human Performance, the textbook the Katch McArdle equation is named after
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This is not medical advice. Body Numbers is a calculator. It does not diagnose, treat or monitor any condition, and no number it produces should replace a conversation with a doctor or a dietitian. If a result worries you, or if you are pregnant, unwell, or under eighteen, speak to a health professional.
