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Lean Body Mass Calculator | Boer Formula

A lean body mass (LBM) calculator estimates fat-free mass from weight, height and sex using the Boer equations: men LBM = 0.407×W + 0.267×H − 19.2; women LBM = 0.252×W + 0.473×H − 48.3 (weight in kg, height in cm). LBM underlies protein requirements, anaesthetic dosing and metabolic rate estimates.

Last updated: September 2026 · Free · No sign-up required

Results

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Quick reference

Typical LBM by build (Boer):

PersonWeightHeightLBM
Small woman55 kg160 cm~41 kg
Average man75 kg178 cm~64 kg
Large athlete95 kg190 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.

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