Katch-McArdle BMR Calculator

Health

Calculate your Basal Metabolic Rate from your lean body mass using the Katch-McArdle formula. Enter your weight and body fat percentage to see your resting calorie needs and lean mass.

Formula

BMR = 370 + (21.6 × Lean Body Mass in kg), Lean Body Mass = Weight × (1 − Body Fat %)
  • The Katch-McArdle formula bases BMR on lean body mass rather than total weight, making it more accurate for lean or muscular people.
  • Lean body mass = weight × (1 − body fat % ÷ 100).
  • BMR = 370 + 21.6 × lean body mass (kg).
  • Because it needs an accurate body fat percentage, its precision depends on how that figure was measured.
  • Multiply BMR by an activity factor (1.2–1.9) to estimate total daily calorie needs.

80 kg at 20% body fat

Inputs
  • Weight (kg): 80
  • Body Fat (%): 20

Lean mass = 80 × 0.80 = 64 kg, so BMR = 370 + 21.6×64 ≈ 1,752 kcal/day.

Frequently asked questions

What is the Katch-McArdle formula?
It estimates BMR from lean body mass, so it accounts for body composition rather than just total weight.
When is it more accurate than other formulas?
It is often better for lean, athletic, or very muscular people, since muscle drives resting metabolism more than fat does.
What do I need to use it?
Your weight and a reasonably accurate body fat percentage, from which the calculator derives your lean body mass.
How is BMR different from TDEE?
BMR is calories at rest. Multiply it by an activity factor to get your total daily energy expenditure including movement.
What if I don't know my body fat %?
Estimate it with a body fat calculator first, or use the Mifflin-St Jeor equation, which only needs height, weight, age, and sex.