Calculators

BMR Calculator

Your basal metabolic rate, the calories your body burns at rest, from three formulas side by side.

How it works

Mifflin-St Jeor (1990) is the equation dietitians now use most, because it predicts measured resting energy use better than the older Harris-Benedict. Katch-McArdle uses lean body mass instead of weight and sex, so it suits people with a known body fat percentage, especially muscular ones. Multiplying BMR by an activity factor gives the calories you burn in a day.

BMR = 10 × kg + 6.25 × cm − 5 × age + 5 (men) or − 161 (women)
BMR
Calories burned at complete rest over 24 hours
Harris-Benedict (revised)
Men: 88.36 + 13.40 kg + 4.80 cm − 5.68 age
Katch-McArdle
370 + 21.6 × lean mass in kg
Activity factor
1.2 sedentary up to 1.9 extremely active

Worked example

A 30-year-old man, 175 cm and 75 kg, who exercises 3–5 days a week.

  1. 110 × 75 = 750
  2. 26.25 × 175 = 1,093.75
  3. 35 × 30 = 150
  4. 4750 + 1,093.75 − 150 + 5 = 1,698.75

His BMR is about 1,699 calories a day, and about 2,633 at a moderately active factor of 1.55.

Frequently asked questions

What is the difference between BMR and TDEE?

BMR is what your body burns lying still all day: breathing, circulation, keeping warm. TDEE, total daily energy expenditure, adds everything you do, from walking to training, and is usually 1.2 to 1.9 times BMR. TDEE is the number to eat around.

Which BMR formula is most accurate?

For most adults Mifflin-St Jeor comes closest, within 10% for about four people in five. Harris-Benedict tends to run a little high. If you know your body fat percentage, Katch-McArdle can be better for lean or very muscular people.

Should I eat less than my BMR to lose weight?

Usually not. A deficit of about 500 calories below your TDEE loses around half a kilo a week and is sustainable. Eating below BMR for long periods makes it harder to keep muscle and to stick to the plan.

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