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BMR Calculator

Calculate your Basal Metabolic Rate (BMR) — the calories your body burns at rest — using the Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle equation, with daily needs by activity level.

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Gender
years

Ages 15–80.

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lb

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Basal Metabolic Rate

1,717Cal/day

Estimated result

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Daily calorie needs by activity level

Activity LevelCalories/day
Sedentary: little or no exercise2,060
Light: exercise 1–3 times/week2,361
Moderate: exercise 4–5 times/week2,515
Active: daily exercise or intense exercise 3–4 times/week2,661
Very Active: intense exercise 6–7 times/week2,962
Extra Active: very intense exercise daily, or physical job3,262
Basal Metabolic Rate1,717 Cal/day

This calculator estimates your Basal Metabolic Rate (BMR) — the calories your body burns at rest — from your sex, age, height, and weight. Pick the equation that fits you, then read the table to see roughly how many calories you'd need each day at different activity levels.

Activity multipliers

Activity levelFactor
Sedentary: little or no exercise1.2
Light: exercise 1–3 times/week1.375
Moderate: exercise 4–5 times/week1.465
Active: daily exercise or intense exercise 3–4 times/week1.55
Very Active: intense exercise 6–7 times/week1.725
Extra Active: very intense exercise daily, or physical job1.9

Examples

Man, 25, 178 cm, 73 kg (Mifflin-St Jeor)

BMR = 10 × 73 + 6.25 × 178 − 5 × 25 + 5 = 730 + 1112.5 − 125 + 5 ≈ 1,723 Cal/day. At a moderate activity factor of 1.465 that's about 2,524 Cal/day.

Man, 25, 178 cm, 73 kg, 20% body fat (Katch-McArdle)

BMR = 370 + 21.6 × (1 − 0.20) × 73 = 370 + 1,261 ≈ 1,631 Cal/day — lower, because it's based on the 58.4 kg of lean mass rather than total weight.

Formula

All three equations work in kilograms (W), centimetres (H), and years (A); US units are converted first.

Mifflin-St Jeor    Men:   BMR = 10W + 6.25H − 5A + 5
                   Women: BMR = 10W + 6.25H − 5A − 161

Harris-Benedict    Men:   BMR = 13.397W + 4.799H − 5.677A + 88.362
                   Women: BMR = 9.247W + 3.098H − 4.330A + 447.593

Katch-McArdle      BMR = 370 + 21.6 × (1 − F) × W      (F = body fat fraction)

Daily calories are then BMR × activity factor.

The original Mifflin study estimated resting energy expenditure from 498 healthy adults aged 19–78. Its equation explained part, not all, of the variation in measured expenditure.

Sources

Frequently asked questions

What is BMR?
Basal Metabolic Rate is the number of calories your body burns at complete rest to keep vital functions running — breathing, circulation, cell production, and temperature regulation. It's measured in a fasted, post-absorptive state and typically accounts for about 60–70% of the calories you burn each day.
Which BMR formula should I use?
Mifflin-St Jeor is the default because it was derived from measured resting expenditure in healthy adults. Revised Harris-Benedict is an alternative, while Katch-McArdle uses estimated lean mass. None measures an individual's metabolism.
What is the difference between BMR and TDEE?
BMR is what you burn at rest. Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor (1.2 for sedentary up to 1.9 for very intense daily activity), and it estimates the calories you actually burn in a typical day.
Why does Katch-McArdle ask for body fat percentage?
Katch-McArdle estimates BMR from lean body mass rather than total weight, so it needs your body fat percentage to subtract fat mass. The other two equations use total weight, height, age, and sex instead, so the body fat field is ignored when they're selected.
How accurate is a BMR calculator?
These equations are population estimates. A 2005 meta-analysis found roughly a 26% unexplained variance between individuals even after controlling for known factors, so treat the result as a solid starting point rather than an exact figure. Indirect calorimetry is required for a precise measurement.

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