Free fitness tool

Lean Body Mass Calculator

Estimate fat-free mass from weight and body-fat percentage.

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How this calculator works

Lean mass equals weight multiplied by one minus body-fat percentage.

How to use your result

Keep your inputs consistent and compare weekly trends. Make small changes only after enough data accumulates.

Important limitation

Calculator results are estimates. Pregnancy, eating disorders, medical conditions, injuries, or concerning symptoms require qualified professional guidance.

Turn these numbers into a plan

RizzFit builds your workouts, calories, and macros around your goal — and adapts as you progress.

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