Because muscle burns more energy than fat, basing BMR on lean mass removes the bias that weight-based equations have for athletes.
How to use the Katch-McArdle BMR Calculator
- Weight
- Body fat
- Activity level
Results update as you type, and every field accepts the units shown in its menu.
How it works
Lean mass is weight times one minus body fat percentage; it is multiplied by 21.6 and 370 is added.
Inputs explained
| Field | What to enter |
|---|---|
| Weight | Units: kg, lb, g, oz, st |
| Body fat | In % |
| Activity level | Choose one: Sedentary, Light, Moderate, Very active … |
What each result means
- Lean body mass = [Weight] × (1 – [Body fat]÷100)
- BMR = 370 + 21.6×[Lean body mass]
- Daily calories (TDEE) = [BMR] × [Activity level]
Example values
How the main result changes when Weight changes and everything else stays at the example values above:
| Weight (kg) | BMR (kcal/day) |
|---|---|
| 40 | 1,078 |
| 60 | 1,433 |
| 80 | 1,787 |
| 100 | 2,141 |
| 120 | 2,495 |
| 160 | 3,204 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
BMR = 370 + 21.6 × lean body mass (kg)Worked example
Inputs — Weight: 80 kg; Body fat: 18 %; Activity level: Moderate.
Results — Lean body mass = 65.6 kg; BMR = 1,787 kcal/day; Daily calories (TDEE) = 2,770 kcal/day.
Frequently asked questions
Why no age or sex?
Their effect is largely captured by lean body mass.
What if my body fat estimate is wrong?
Errors in body fat carry directly into the result.
What formula does the Katch-McArdle BMR Calculator use?
BMR = 370 + 21.6 × lean body mass (kg).