Fitness & Performance
Katch-McArdle BMR Calculator
Standard BMR formulas misfire for muscular builds. Katch-McArdle works from lean body mass, the part of you that actually burns the calories.
The Katch-McArdle formula estimates basal metabolic rate from lean body mass rather than total weight: BMR = 370 + 21.6 × lean body mass in kilograms. It's more accurate for muscular or lean individuals than standard equations. Use the result as a training benchmark — retest under the same conditions to track progress.
Uses lean mass, not total weight.
Better for athletes and lifters.
Needs body fat % as input.
Calculate Your Katch-McArdle BMR
Your BMR
What Is Katch-McArdle BMR?
The Katch-McArdle equation estimates BMR from lean body mass, muscle, bone, organs, and water, instead of total weight. Because lean tissue does nearly all the metabolic work, this removes a major error source.
It's the preferred formula for athletes, bodybuilders, and anyone who knows their body fat percentage. The trade-off: it requires that extra input.
How It Is Calculated
Katch-McArdle: BMR = 370 + 21.6 × lean body mass (kg)
Lean body mass = weight × (1 − body fat % ÷ 100)
Example: Example: 80 kg at 15% body fat → 68 kg lean mass → BMR ≈ 1,839 kcal/day
Katch-McArdle vs standard formulas
| Formula | Inputs | Best for |
|---|---|---|
| Katch-McArdle | Weight + body fat % | Athletes, lifters, lean builds |
| Mifflin-St Jeor | Weight + height + age + sex | General population |
| Harris-Benedict | Weight + height + age + sex | General population (older) |
Limitations
- Accuracy depends on an accurate body fat input.
- Assumes average organ and bone metabolism.
- Not needed if you're close to average body composition.
Sources & Review
References used for this calculator’s formulas and thresholds:
Katch-McArdle BMR FAQ
Why use Katch-McArdle instead of Mifflin-St Jeor?
Because it uses lean mass rather than total weight, it avoids overestimating BMR in muscular people and underestimating it in very lean ones.
How do I get my body fat percentage?
Skinfold calipers, bioelectrical impedance scales, or DEXA. Navy circumference estimates are fine for this purpose, the formula tolerates ±3% error well.
Does more muscle really burn more calories?
Yes, muscle is metabolically active tissue. Each kilogram of added lean mass raises resting burn by roughly 20 kcal/day.
What if I don't know my body fat?
Use the standard BMR calculator instead, or estimate body fat with the body fat calculator first.
Important disclaimer: Results are educational estimates, not a substitute for professional advice. Review your numbers with a qualified advisor before acting on them.