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Lean Body Mass Calculator

Boer formula lean body mass from weight and height.

Best for: Use it when cutting to make sure the weight you lose is fat, not muscle.

Complete guide
See benchmark ranges Why this result happened View assumptions
Country (units):

Input

How it's calculated & sources
The Lean Body Mass Calculator uses the standard formula for this calculation. It runs entirely in your browser, so your inputs are never uploaded. Figures are educational estimates, not professional advice — verify important decisions with a qualified expert. Last reviewed June 2026.
Key assumptions
  • Formula estimate (Boer/Hume)

Educational estimate only — not medical advice. Consult a qualified healthcare professional for decisions about your health.

Free & no sign-up · runs entirely in your browser. Results are estimates for general information, not professional advice — verify important decisions with a qualified expert. Last reviewed June 2026.

How it works

Boer formula:

Men: 0.407·kg + 0.267·cm − 19.2

Women: 0.252·kg + 0.473·cm − 48.3

Example

Male 70 kg, 175 cm → 0.407·70 + 0.267·175 − 19.2 ≈ 56.0 kg LBM.

Frequently asked questions

What is LBM?+

Total body weight minus fat — muscle, bone, organs, water.

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Complete guide

Quick answers

Short, sourced answers to the questions people (and AI assistants) ask most.

What is Lean Body Mass?
Lean body mass (LBM) is everything in your body that isn't fat \u2014 muscle, bone, organs and water. It's a useful baseline for nutrition and dosing.
Why does Lean Body Mass matter?
It feeds BMI, calorie, body-fat and dosing calculations.
How is Lean Body Mass calculated?
It subtracts your fat mass from total weight, using either your body-fat % or a validated formula (Boer) from height and weight. Formula: LBM = weight \u2212 (weight \u00d7 body-fat %).
What is a good lean body mass?
Men ~10-20%, Women ~18-28% (fit)
What are common lean body mass mistakes?
Tape estimates are approximate (about +/-3-4%)
When should you use the Lean Body Mass Calculator?
Use it when cutting to make sure the weight you lose is fat, not muscle.

What is the Lean Body Mass Calculator?

Lean body mass (LBM) is everything in your body that isn't fat \u2014 muscle, bone, organs and water. It's a useful baseline for nutrition and dosing.

How the Lean Body Mass Calculator works

It subtracts your fat mass from total weight, using either your body-fat % or a validated formula (Boer) from height and weight.

LBM = weight \u2212 (weight \u00d7 body-fat %)
  • weight — Total body weight
  • body-fat % — From a body-fat estimate
  1. Enter your weight — your body weight, entered in kilograms or pounds.
  2. Enter your height — your height, entered in centimeters/meters or feet and inches.
  3. Enter your body fat percentage — the share of your body weight that is fat.
  4. Read the result, then change any input to compare scenarios instantly — the Lean Body Mass Calculator recalculates as you type.

Understanding the inputs

What each value means, why it matters, and a typical range — so you can fill in the calculator with confidence.

Weight

Your body weight, entered in kilograms or pounds.

Why it matters:
It feeds BMI, calorie, body-fat and dosing calculations.
Typical range:
Varies by person; tools accept metric or imperial.
How it affects results:
  • Higher: Raises BMI and calorie needs.
  • Lower: Lowers BMI and calorie needs.

Common mistake: Mixing units - entering pounds where kilograms are expected.

Height

Your height, entered in centimeters/meters or feet and inches.

Why it matters:
It is paired with weight to judge healthy ranges and body composition.
Typical range:
Varies by person.
How it affects results:
  • Higher: A given weight reads as a lower BMI.
  • Lower: A given weight reads as a higher BMI.

Common mistake: Entering centimeters where meters are expected, or mixing units.

Body Fat Percentage

The share of your body weight that is fat.

Why it matters:
It reflects fitness and health better than weight or BMI alone.
Typical range:
Roughly 10% to 20% for fit men, 18% to 28% for fit women.
How it affects results:
  • Higher: More fat mass.
  • Lower: Leaner composition (very low can be unhealthy).

Common mistake: Trusting a single tape reading over the trend across weeks.

Benchmark reference

What counts as poor, average or excellent for this metric.

Body Fat

PoorVery high
Below averageAbove average
AverageAverage
Above averageFitness
ExcellentAthletic

Source: ACE / ACSM general ranges · Updated June 2026

Typical values

Body Fat:
Men ~10-20%, Women ~18-28% (fit)

Common interpretation errors

  • Tape estimates are approximate (about +/-3-4%)
  • Healthy ranges differ by sex and age
  • Track the trend, not one reading

What impacts results most

  1. 1.
    Body weight (High impact)LBM is weight minus fat mass.
  2. 2.
    Body fat % / height (High impact)Determines the fat portion removed.

Key assumptions

  • Formula estimate (Boer/Hume)

Lean body mass by weight at 175 cm height (Boer formula)

60 kg51.9 kg49.6 kg
70 kg56 kg52.1 kg
80 kg60.1 kg54.6 kg
90 kg64.2 kg57.2 kg
100 kg68.2 kg59.7 kg

Worked example

Inputs: Weight 70 kg, body fat 20% Calculation: LBM = weight × (1 − body-fat%) Result: 56 kg lean mass What it means: Track lean mass alongside weight so a 'plateau' isn't actually muscle gain plus fat loss.

Compared to alternatives

Lean Mass vs Body Fat

Two sides of body composition.

Lean MassBody Fat %
MeasuresFat-free weightShare that is fat
Rises whenYou build muscleYou gain fat
Use forTracking muscleTracking fat loss

Bottom line: Watch both — holding lean mass while fat drops is the real recomposition goal.

Lean Mass calculator·Body Fat % calculator

Related concepts

How Lean Body Mass connects to the concepts around it.

Body Fat:
The share of body weight that is fat.
Body Composition:
The body's make-up of fat versus lean mass.
Protein:
The daily protein needed to build or keep muscle.
One-Rep Max:
The most you can lift once, a strength benchmark.

Fitness learning path

A sensible order to learn these concepts.

Body CompositionLean Body MassProteinOne-Rep Max

Reviewed sources & methodology

Methodology: Professional Estimate · Last reviewed June 2026.

Keywords: lbm, lean, muscle.

This tool is for general information only and is not medical advice. Consult a qualified healthcare professional for decisions about your health.

Reviewed by the Free Tools Galaxy editorial team · Updated June 2026 · Calculated privately in your browser.

Frequently asked questions

Is the Lean Body Mass Calculator free to use?+

Yes. Every tool on Free Tools Galaxy is 100% free, runs in your browser and requires no signup.

How accurate is the Lean Body Mass Calculator?+

Lean Body Mass Calculator uses the standard lean body mass formula in double-precision arithmetic, so the same inputs always produce the same result and you can verify any figure by hand. It is an educational estimate — real-world outcomes depend on your actual rates, rules and assumptions.

Do you store my inputs?+

No. The Lean Body Mass Calculator runs entirely in your browser. Nothing is uploaded or saved to a server.

Can I use the Lean Body Mass Calculator on mobile?+

Yes — the interface is fully responsive and works on phones, tablets and desktops.

What are common mistakes to avoid?+

The most frequent mistake is mixing units. Double-check your inputs use a single, consistent unit before clicking Calculate.

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Boer formula lean body mass from weight and height.

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