Comprehensive Calculator Guide
Lean body mass is everything you weigh except fat: muscle, bone, organs and water. This calculator estimates it from weight, height and sex with the Boer formula, along with fat mass and body fat percentage. A man of 80 kg and 178 cm has about 60.9 kg of lean mass.
The Boer formula and its limits
Boer's 1984 formula uses weight in kg and height in cm: for men 0.407W + 0.267H − 19.2, for women 0.252W + 0.473H − 48.3. Fat mass is weight minus lean mass.
It is based on averages and cannot tell muscle from fat, so it tends to underestimate lean mass in very muscular people. DEXA scans or body composition analysers are more accurate; use the calculator to follow trends.
How to Use
- 01Choose your sex.
- 02Enter weight and height.
- 03Read lean mass, fat mass and body fat percentage.
Formula Used
Men: 0.407W + 0.267H − 19.2 | Women: 0.252W + 0.473H − 48.3Practical Examples
Example 1: a man
80 kg, 178 cm: 60.9 kg lean, about 23.9% fat.
Example 2: a woman
65 kg, 165 cm: 46.1 kg lean, about 29% fat.
Important Tips
- Resistance training and enough protein help keep lean mass while losing weight.
Common Mistakes to Avoid
- Treating the estimate as a precise measurement.
- Using it for children.
Frequently Asked Questions
- What is lean body mass?
- Body weight minus fat.
- Is it the same as muscle?
- No, it also includes bone, organs and water.
- Is it accurate for athletes?
- Less so; it may underestimate their lean mass.