Free calculator

BMR calculator

How many calories your body burns at complete rest — the energy it spends just keeping you alive — and your whole day on top of it.

Units
Sex
Age
Weight
Height
At rest
1,450
kcal a day · Mifflin–St Jeor

About 61 kcal an hour, even asleep

Harris–Benedict
1,490 kcal a day
Your whole day, by activity
Mostly sitting
1,740
Lightly active
2,000
Moderately active
2,250
Very active
2,510
Athlete
2,760

A formula is a first guess: real people differ from it by hundreds of calories a day. Your own diary and a few weigh-ins tell the real number.

For healthy adults. Not medical advice — if you are pregnant, have a medical condition or take medicines that affect appetite, ask your doctor.

Let your diary find the real number

foodoo starts from this formula, then reads your own food log and weight trend and moves the target towards what you really burn — no calculator needed after the first day.

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What basal metabolic rate is

BMR is the energy your body uses lying still and awake: the heart beating, breathing, the brain, the liver and kidneys at work, keeping warm. For most people it is 60–70% of everything they burn in a day — more than all exercise put together.

It depends mostly on size and on how much of you is muscle and organs: bigger and more muscular bodies burn more. It falls slowly with age, and is usually lower in women than in men of the same weight.

Two equations

Mifflin–St Jeor (1990) is the equation reviews found most accurate for most healthy adults, within about 10% for two people in three. Harris–Benedict is older (1919, revised in 1984) and tends to come out a little higher. The two side by side show how much of the answer is guesswork.

Neither knows your body composition. A very muscular person burns more than either says; someone with a lot of body fat, often less.

From BMR to your day

Multiply BMR by your activity — from 1.2 when mostly sitting to 1.9 for athletes — and you get your total daily energy expenditure (TDEE), the number that matters for eating. Never eat below your BMR for long without a doctor: the body has to find that energy somewhere.

Questions

What is the difference between BMR and RMR?
BMR is measured in strict conditions — after a night's sleep and a 12-hour fast; RMR (resting metabolic rate) under easier ones, so it comes out slightly higher. In everyday use the words mean nearly the same.
Can I raise my BMR?
A little, by building muscle with strength training. Most of the difference between people comes from size, age and sex, which you cannot change.
Does dieting lower BMR?
Yes: a lighter body burns less, and during a deficit the body saves a little more on top. Keeping protein up and doing strength training limits it.
Which BMR equation is most accurate?
For most healthy adults, Mifflin–St Jeor. If you know your body fat percentage, Katch–McArdle can be closer, especially for very lean or muscular people.

Sources

  1. Mifflin MD et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr, 1990.
  2. Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. Am J Clin Nutr, 1984.
  3. Frankenfield D et al. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc, 2005.