Lean Body Mass Calculator

Lean body mass (LBM) is your total weight minus all body fat. It includes muscle, bone, organs, blood, and water. For a 80 kg person at 20% body fat, LBM is 64 kg.

For men, LBM typically ranges from 60–85 kg depending on height and build. An athletic 180 cm male will often have LBM of 70–80 kg. More useful than a single number is tracking whether your LBM is stable or increasing over time — rising LBM with stable or falling weight means you're building muscle while losing fat.

For women, LBM typically ranges from 40–60 kg depending on height and frame. A 165 cm woman at a healthy body fat of 22–28% will usually carry 44–55 kg of lean mass. Women naturally carry a higher essential fat % than men (10–13% vs 2–5%), so a lower absolute LBM is normal and healthy.

BMI divides weight by height squared — it can't tell muscle from fat. A 90 kg bodybuilder and a 90 kg sedentary person have the same BMI but very different body compositions. LBM directly measures the non-fat component, making it far more useful for fitness and nutrition planning.

The Boer formula estimates LBM from weight and height. For males: LBM = 0.407×W(kg) + 0.267×H(cm) − 19.2. For females: LBM = 0.252×W(kg) + 0.473×H(cm) − 48.3. It was validated in a large clinical study and is considered more accurate than older formulas like James or Hume, especially for average-weight adults.

No — lean body mass includes muscle, bone, organs, blood, and water. Skeletal muscle is typically 40–50% of LBM in men and 35–40% in women. When people say they want to 'build lean mass,' they usually mean muscle, but an increasing LBM number on the scale could also reflect bone density improvements or increased hydration.

Protein recommendations for building or preserving muscle are based on LBM, not total weight. Targeting 1.6–2.2 g of protein per kg of LBM is more precise than per kg of total body weight, especially for overweight individuals. A 100 kg person at 30% body fat has an LBM of 70 kg and needs 112–154 g of protein, not 160–220 g.

Yes — LBM decreases with age (a process called sarcopenia), during prolonged calorie deficits without adequate protein, with inactivity, and after illness or injury. Resistance training and sufficient protein intake (1.6+ g/kg LBM) are the most effective ways to preserve or increase LBM at any age.

DEXA (dual-energy X-ray absorptiometry) is the gold standard — it measures bone density, lean mass, and fat mass precisely in each body region. Formula-based estimates have ±3–5 kg error on average. If you have access to a DEXA or InBody scan, enter your body fat % into this calculator for a direct, more accurate LBM.

There's no universal answer, but most research shows optimal performance and health at 10–20% body fat for men and 18–28% for women. At these ranges, LBM-to-total-weight ratio is high while hormone function, recovery, and energy remain normal. Going below 5% (men) or 12% (women) risks hormone disruption and reduced LBM as the body catabolises muscle.

The three pillars are: (1) progressive resistance training 3–5 days per week, (2) protein intake of 1.6–2.2 g/kg of LBM, and (3) a slight calorie surplus (200–300 kcal above TDEE) to support muscle protein synthesis without excessive fat gain. Sleep (7–9 hours) and consistency over months matter more than any single tactic.

Only if you know your body fat percentage. If BF% is available, enter it and leave the height field blank — the calculator will use the direct method (LBM = weight × (1 − BF%/100)), which requires only weight and body fat.