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BMR Calculator

Find your basal metabolic rate: the calories your body burns at complete rest. The BMR calculator also turns it into your daily need at five activity levels.

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Sex

Units

Basal metabolic rate
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For general information. Not medical advice.

How to use the BMR Calculator

  1. Choose your Sex and enter your Age.
  2. Enter your height and weight in metric or US units, and pick a Formula. Katch-McArdle also asks for your body fat percentage.
  3. Press Calculate. You get your BMR in kcal a day, followed by your total daily need at each activity level.

How it works

Mifflin-St Jeor:  10 × kg + 6.25 × cm − 5 × age + 5     (male)
                  10 × kg + 6.25 × cm − 5 × age − 161   (female)
Harris-Benedict:  88.362 + 13.397 × kg + 4.799 × cm − 5.677 × age   (male)
                  447.593 + 9.247 × kg + 3.098 × cm − 4.330 × age   (female)
Katch-McArdle:    370 + 21.6 × lean mass (kg)
Daily need (TDEE) = BMR × activity factor
  • kg, cm, age: weight, height, and age in years
  • lean mass: weight × (1 − body fat % ÷ 100)
  • activity factor: 1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 active, 1.9 very active

Examples

  • Male, 30, 180 cm, 80 kg (Mifflin-St Jeor): 800 + 1,125 − 150 + 5 = 1,780 kcal/day. With moderate exercise, 1,780 × 1.55 = 2,759 kcal.
  • Female, 30, 165 cm, 60 kg: 600 + 1,031.25 − 150 − 161 = 1,320 kcal/day.

Which BMR formula should I use?

Mifflin-St Jeor, published in 1990, is the default. A 2005 systematic review for the American Dietetic Association found it the most reliable of the common equations: it came within 10% of measured resting metabolic rate for more people than the others. The revised Harris-Benedict equation from 1984 tends to come out a little higher. Katch-McArdle ignores sex and age and works from lean body mass, so it suits lean, muscular people who know their body fat percentage.

All three are estimates. Even Mifflin-St Jeor misses the measured value by more than 10% for some people, because muscle, genetics, and hormones differ between two people with the same height, weight, and age.

Limitations

  • The formulas are for adults. Ages 15 to 100 are accepted.
  • BMR is measured lying still after fasting. Your real daily burn also depends on digestion, fidgeting, and exercise.
  • The activity factors are broad averages. Adjust your intake if your weight moves differently than expected over a few weeks.

Sources

Frequently asked questions

What is the difference between BMR and TDEE?

BMR is what you burn at complete rest. TDEE, total daily energy expenditure, is BMR multiplied by an activity factor, so it includes movement and exercise.

Why is my BMR lower than I expected?

BMR covers only the energy for breathing, circulation, and keeping organs working. Most people burn 20% to 90% more than their BMR over a full day.

Does muscle raise BMR?

Yes. Muscle uses more energy at rest than fat, which is why the Katch-McArdle formula works from lean mass.

Often used together with BMR Calculator.