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Lean Body Mass Calculator | Boer Formula

Quick reference

Typical LBM by build (Boer):

Person	Weight	Height	LBM
Small woman	55 kg	160 cm	~41 kg
Average man	75 kg	178 cm	~64 kg
Large athlete	95 kg	190 cm	~83 kg

egg_alt Protein math

At 2 g/kg LBM, a 61 kg-lean athlete targets ~122 g protein daily — far more sensible than 2 g/kg total weight for heavier individuals.

local_fire_department Metabolic engine

Lean mass burns the majority of resting calories, so two people of equal weight can differ 200+ kcal/day in BMR.

medication Clinical dosing

Some anaesthetics and chemotherapy agents reference LBM or adjusted weight — never dose those by total weight alone.

monitoring Track the trend

During a cut, LBM should hold steady while weight falls; a falling LBM estimate signals too-aggressive dieting.

lightbulb A real example — protein target for a 75 kg man

75 kg, 178 cm, male, training for strength.

Result: LBM ≈ 64 kg; at 2 g/kg that's a 128 g daily protein target.

What this means: Compare with 150 g (2 g/kg total weight) — the LBM view avoids overfeeding protein while cutting.

Formula & methodology

Formula: Men: LBM = 0.407×W + 0.267×H − 19.2; Women: LBM = 0.252×W + 0.473×H − 48.3

The Boer equation (1984)

Boer estimated fat-free mass directly from height and weight without a body-fat measurement. For a 70 kg, 175 cm man: LBM = 0.407×70 + 0.267×175 − 19.2 ≈ 61 kg.

LBM includes muscle, bone, organs and water — everything except storage fat. Practical uses:

Protein targets are often set at 1.6–2.2 g per kg LBM for lifters, not per kg total weight.
Drug dosing: some anaesthetics and toxins dose on LBM (or adjusted body weight) because adipose tissue barely participates.
Metabolic rate: roughly 90% of resting energy use comes from lean mass, so LBM predicts BMR better than weight.

Frequently asked questions

How is lean body mass calculated?

The Boer formula estimates it from height and weight: men LBM = 0.407×W + 0.267×H − 19.2; women LBM = 0.252×W + 0.473×H − 48.3, with kg and cm.

Is lean body mass the same as muscle mass?

No. LBM counts everything except fat — muscle, organs, bone and water. Skeletal muscle is only about half of LBM.

How much protein should I eat per kg of lean mass?

Evidence-backed muscle-building targets are 1.6–2.2 g per kg LBM per day; per kg of total weight over-prescribes protein for people with higher body fat.

What is a normal lean body mass?

It scales with height and sex: roughly 60–65% of total weight for men and 65–72% for women in healthy ranges — about 61 kg LBM for an average 75 kg man.

How accurate is the Boer formula compared to a DEXA scan?

Boer was validated against underwater weighing with errors around ±2–3 kg for typical adults — fine for protein targets and calorie estimates, but not precise enough for tracking small recomposition changes. Accuracy falls for the very lean and the very obese, where the height–weight relationship breaks down. Use it for planning; use DEXA or a Bod Pod if you need lab-grade numbers.

What is the difference between the Boer, James and Hume formulas?

All three estimate LBM from height, weight and sex but were fitted on different populations: Boer (1984) on a general adult sample, James on a smaller clinical group, Hume on a mixed hospital population. For most people they agree within 1–2 kg. Boer is the most widely cited in sports nutrition, which is why this calculator uses it.

Does lean body mass decline with age?

Yes — adults typically lose 3–8% of muscle mass per decade after 30, accelerating after 60, a process called sarcopenia. Because the Boer formula only sees height and weight, it will not show this decline unless weight drops too: two 80 kg men aged 30 and 70 get the same estimated LBM but have very different actual muscle. Strength training and adequate protein are the main brakes on the loss.

Should I dose creatine or protein by total weight or lean mass?

Lean mass. A 100 kg lifter at 15% body fat and one at 30% body fat have very different metabolically active tissue but identical total weight. Protein targets of 1.6–2.2 g/kg LBM and creatine scaled to LBM avoid overfeeding the higher-fat lifter. Most supplement labels use total weight for simplicity, which is a reasonable shortcut only near healthy body-fat levels.

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