# Lean Body Mass Calculator

URL: https://speedycalculator.com/calculators/health/lean-body-mass/
Last updated: 2026-10-25

> The lean body mass calculator estimates the weight of everything in your body except fat, using the Boer formula from height, weight and sex. It also shows estimated body fat mass and percentage.

## Inputs

- Sex
- Weight (kg, lb, g, oz, st)
- Height (cm, m, mm, in, ft)

## Results

- Lean body mass
- Estimated fat mass
- Estimated body fat

## Formula

```
Men: LBM = 0.407W + 0.267H − 19.2
Women: LBM = 0.252W + 0.473H − 48.3   (W kg, H cm)
```

## Explanation

Lean mass includes muscle, bone, organs and water. It is used in drug dosing and to set protein targets.

### How to use the Lean Body Mass Calculator

- **Sex**
- **Weight**
- **Height**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

The Boer equation predicts lean mass from weight and height; the rest of your weight is treated as fat.

### Inputs explained

FieldWhat to enterSexChoose one: Male, FemaleWeightUnits: kg, lb, g, oz, stHeightUnits: cm, m, mm, in, ft

### What each result means

- **Estimated fat mass** = [Weight] - [Lean body mass]
- **Estimated body fat** = [Estimated fat mass] ÷ [Weight] × 100

### Example values

How the main result changes when **Weight** changes and everything else stays at the example values above:

Weight (kg)Lean body mass (kg)4045.16053.38061.410069.612077.716094
*Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.*

## Worked example

Inputs — Sex: Male; Weight: 80 kg; Height: 180 cm.

Results — **Lean body mass = 61.4 kg**; Estimated fat mass = 18.6 kg; Estimated body fat = 23.2 %.

## Key terms

- **Lean body mass**: Body weight minus fat mass.

## FAQ

**How accurate is this?**
Formula estimates can be several kilograms off; DEXA scans are more precise.

**Is lean mass the same as muscle mass?**
No, it also includes bone, organs and water.

**What formula does the Lean Body Mass Calculator use?**
Men: LBM = 0.407W + 0.267H − 19.2.


## Sources

- [Boer P. Estimated lean body mass as an index for normalization of body fluid volumes in humans. Am J Physiol, 1984](https://pubmed.ncbi.nlm.nih.gov/6496691/)