Katch-McArdle BMR & TDEE Calculator
The Katch-McArdle formula uses lean body mass to estimate basal metabolic rate. Provide your weight and body fat percentage to see resting calorie needs and total daily energy expenditure.
Use body composition measurements or caliper estimates for best accuracy.
Katch-McArdle Results
Lean mass
61.5 kg
BMR
1698 kcal/day
TDEE
2633 kcal/day
Activity factor ×1.550
Converted weight: 75.0 kg
How to Use This Calculator
Measure body composition
Use calipers, bioimpedance, DEXA, or other methods to estimate body fat percentage. Lean mass accuracy directly affects the result.
Enter weight and choose units
Provide current body weight and select metric or imperial units. The calculator converts to kilograms before applying the formula.
Review BMR and TDEE
BMR is the resting calorie requirement; TDEE reflects daily needs after accounting for activity. Adjust calorie intake relative to TDEE to gain or lose weight.
Formula
Lean Body Mass (kg) = Weight (kg) × (1 − Body Fat % ÷ 100)
BMR = 370 + 21.6 × Lean Body Mass (kg)
TDEE = BMR × Activity Factor
- 21.6 is the energetic cost per kilogram of lean mass in the Katch-McArdle model.
- Activity factors range from 1.2 (sedentary) to ~1.9 (extra active).
- Ensure weight is converted to kilograms before computing lean mass.
Full Description
The Katch-McArdle equation estimates basal metabolic rate using lean body mass instead of total body weight. This makes it particularly useful for athletes and individuals with higher or lower muscle mass than the general population. Because lean mass is metabolically active, basing calculations on fat-free mass can improve accuracy compared to weight-based formulas.
Use the resulting BMR as a foundation for nutrition planning. Multiply by an activity factor to get total daily energy expenditure, then adjust caloric intake to match weight-management goals. Regularly update body fat measurements to keep estimates current.
Frequently Asked Questions
How do I measure body fat for this calculator?
Skinfold calipers, bioelectrical impedance (smart scales), Bod Pod, or DEXA scans can provide body fat estimates. Use the most reliable method available.
What if I do not know my body fat percentage?
Consider using a Mifflin–St Jeor or Harris-Benedict calculator, which rely on height and weight. Katch-McArdle requires body fat to compute lean mass.
How should I use the TDEE value?
TDEE is the estimated maintenance level. Create deficits (−250 to −500 kcal/day) to lose weight or surpluses (+250 to +500 kcal/day) to gain weight.
Does activity factor include strength training?
Yes. Choose the factor that best represents your overall weekly exercise volume, including cardiovascular and resistance training.