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Lean body mass is your total body weight minus fat mass — muscle, bone, organs, and water. It's a more precise way to track body composition changes than weight alone.
This calculator estimates lean body mass using the Boer formula, one of the most widely cited equations for this purpose.
How it works
Enter your weight, height, and sex. The calculator applies the Boer formula — which uses different coefficients for men and women — to estimate lean body mass, then subtracts it from total weight to estimate fat mass.
- Enter weight (kg).
- Enter height (cm).
- Enter sex.
- Click Calculate to see your results.
Examples
A 70kg, 175cm male
Using the Boer formula, this works out to about 56 kg of lean body mass — roughly 80% of total body weight.
Who should use it
- Tracking body composition changes during a training program.
- Estimating protein needs based on lean mass rather than total weight.
Industry applications
- Fitness and strength training
- Sports science and nutrition planning
Advantages
- Uses a well-established formula requiring only weight, height, and sex.
- Shows both lean mass and estimated fat mass.
Limitations
- Less accurate than direct measurement methods like DEXA scans or skinfold calipers.
Common mistakes to avoid
- Treating this estimate as precise as a DEXA scan or other clinical body composition measurement.
- Entering height in inches or weight in pounds without converting to centimeters and kilograms first.
Best practices
- Track lean body mass trends over time rather than focusing on a single estimate, since formula-based methods carry more uncertainty than direct measurement.
Tips
- For more precise protein target planning, some coaches recommend basing intake on lean body mass rather than total body weight, especially for people carrying more body fat.