Lean Body Mass Calculator

Estimate how many kilograms of you are lean tissue — muscle, bone and organs — and what that implies for body fat.

Why Lean Body Mass Matters

LBM drives your resting metabolism — more lean tissue means a higher BMR. Tracking it (rather than just weight) shows whether you're losing muscle or fat while dieting.

Resistance training and adequate protein preserve LBM during a cut.
Boer is most accurate for average adults; very muscular people may see slight overestimates of fat.

Frequently Asked Questions

What is lean body mass?

Everything in your body that isn't fat: muscle, bones, organs, blood and water.

How accurate is the Boer formula?

Within a few percent of DEXA for most healthy adults — good for tracking trends over time.

Why does sex affect the formula?

Women naturally carry a higher percentage of essential fat, so the formula accounts for that baseline.

How do I build lean mass?

Progressive strength training plus 1.6-2.2 g protein per kg daily, with enough total calories.

Practical Example

A 75 kg man who is 180 cm tall:

Boer lean body mass ≈ 60.5 kg
Body fat ≈ 75 − 60.5 = 14.5 kg (19.3%)

What Your Results Mean

Lean body mass — your fat-free weight: muscle, bone, organs and water.
Body fat — total weight minus lean mass.
Tracking lean mass over time is a better progress metric than weight alone.