What is lean body mass?
Lean body mass (LBM) is your total weight minus your fat: muscle, bone, organs, connective tissue and water. It's a useful number because your metabolism, strength and protein needs all scale with lean mass, not total weight. Two people at the same weight can have very different LBM.
How it's calculated
- From body fat % (most accurate): LBM = weight × (1 − body fat% ÷ 100).
- Boer, James & Hume formulas estimate LBM from height and weight when body fat is unknown. Boer is a solid default for most adults.
Lean body mass chart
Estimated lean body mass in kg by height and weight, using the Boer formula — the calculator's default when you don't enter a body-fat percentage. Find your height on the left and your weight across the top. Body fat is roughly your weight minus the figure shown.
| Men | 60 kg | 70 kg | 80 kg | 90 kg | 100 kg | 110 kg |
|---|---|---|---|---|---|---|
| 160 cm | 47.9 | 52 | 56.1 | 60.1 | 64.2 | 68.3 |
| 165 cm | 49.3 | 53.3 | 57.4 | 61.5 | 65.6 | 69.6 |
| 170 cm | 50.6 | 54.7 | 58.7 | 62.8 | 66.9 | 71 |
| 175 cm | 51.9 | 56 | 60.1 | 64.2 | 68.2 | 72.3 |
| 180 cm | 53.3 | 57.4 | 61.4 | 65.5 | 69.6 | 73.6 |
| 185 cm | — | 58.7 | 62.8 | 66.8 | 70.9 | 75 |
| 190 cm | — | 60 | 64.1 | 68.2 | 72.2 | 76.3 |
| 195 cm | — | — | 65.4 | 69.5 | 73.6 | 77.6 |
| Women | 50 kg | 60 kg | 70 kg | 80 kg | 90 kg |
|---|---|---|---|---|---|
| 150 cm | 35.3 | 37.8 | 40.3 | 42.8 | 45.3 |
| 155 cm | 37.6 | 40.1 | 42.7 | 45.2 | 47.7 |
| 160 cm | 40 | 42.5 | 45 | 47.5 | 50.1 |
| 165 cm | — | 44.9 | 47.4 | 49.9 | 52.4 |
| 170 cm | — | 47.2 | 49.8 | 52.3 | 54.8 |
| 175 cm | — | 49.6 | 52.1 | 54.6 | 57.2 |
| 180 cm | — | 52 | 54.5 | 57 | 59.5 |
Cells marked — fall below a healthy BMI (18.5). The Boer formula overestimates lean mass for very slim builds, so no figure is shown there — enter a body-fat % in the calculator for a reliable number.
Why LBM matters
- Protein: targets are often set per kg of lean mass (roughly 1.6–2.2 g/kg of bodyweight, higher relative to LBM when lean).
- Metabolism: the Katch-McArdle BMR formula uses lean mass directly — see the TDEE calculator.
- Progress: when dieting, preserving LBM (not just losing weight) is the real goal.
What is my lean body mass?
It depends on your height, weight and sex. An 80 kg, 180 cm man has an estimated LBM of about 61.4 kg (135 lb); a 65 kg, 165 cm woman, about 46.1 kg (102 lb). Enter your own numbers above, or find them in the chart.
How do you calculate lean body mass?
The Boer formula is the most widely used: for men, LBM = 0.407 × weight (kg) + 0.267 × height (cm) − 19.2; for women, 0.252 × weight + 0.473 × height − 48.3. If you know your body fat %, it's simpler and more accurate: LBM = weight × (1 − body fat %).
LBM vs fat-free mass — same thing?
Almost. "Fat-free mass" excludes all fat; "lean body mass" technically includes a small amount of essential fat. In everyday use they're treated as the same.
Which formula should I trust?
If you know your body fat %, use that — it's the most personal. Otherwise Boer is a reliable general estimate; the three usually agree within a kilogram or two.
How do I raise my LBM?
Resistance training plus enough protein and calories builds muscle. Get your body fat with the body fat calculator to track lean gains over time.