Which formula does this use?

The Boer formula, a well-validated equation that estimates LBM from weight, height and sex. It is a population estimate, not a direct measurement like a DEXA scan.

No. The Boer formula runs entirely in your browser and none of your inputs are sent to a server or stored.

What is the Boer formula for lean body mass?

For men, LBM = 0.407 × weight(kg) + 0.267 × height(cm) − 19.2. For women, LBM = 0.252 × weight(kg) + 0.473 × height(cm) − 48.3. Weight must be in kilograms and height in centimetres.

How accurate is a Boer-formula estimate?

The Boer equation is one of the more accurate population formulas for adults of typical body composition, but it is still an estimate. For a precise figure use a DEXA scan, hydrostatic weighing or a calibrated bioimpedance device.

Why do I need lean body mass?

Lean body mass is used to set protein targets, calculate certain drug dosages, track muscle gain during training, and compute resting metabolic rate more precisely than body weight alone.

Does the calculator give my body-fat percentage too?

Yes. It subtracts lean mass from total weight to get fat mass, then divides fat mass by total weight to show an approximate body-fat percentage alongside the lean figure.

Lean Body Mass Calculator

Q: What is lean body mass?

Lean body mass (LBM), also called fat-free mass, is everything in your body that is not fat — muscle, bone, organs and water. It is useful for setting protein targets and drug dosing.

Your lean body mass (LBM), also called fat-free mass, is everything in your body that is not fat — muscle, bone, organs and water. This calculator estimates it from your height, weight and sex using the Boer formula, a widely cited equation used in sports nutrition and clinical dosing. It is for adults tracking body composition, setting protein goals or estimating metabolic rate.

How it works

The tool converts your input to metric (kilograms and centimetres) if needed, then applies the Boer formula:

Men: LBM = 0.407 × weight(kg) + 0.267 × height(cm) − 19.2
Women: LBM = 0.252 × weight(kg) + 0.473 × height(cm) − 48.3

It then derives two more figures: fat mass = total weight − LBM, and body-fat % = fat mass ÷ total weight × 100. Imperial inputs are converted first (1 lb = 0.453592 kg, height in inches × 2.54 = cm) so the formula always runs on metric values.

Example

A 178 cm, 75 kg man:

LBM = 0.407 × 75 + 0.267 × 178 − 19.2 = 30.53 + 47.53 − 19.2 = 58.9 kg

Result	Value
Lean body mass	58.9 kg
Fat mass	16.1 kg
Body-fat (approx)	21.5%

The Boer formula runs entirely in your browser — none of your inputs are uploaded or stored.