Lean Body Mass Calculator
Calculate your Lean Body Mass across four validated formulas — with a full body composition breakdown, ideal LBM range, training targets, and a roadmap to your goal physique.
Your results will appear here
Fill in the form and press “Calculate My Lean Body Mass”.
What is lean body mass?
Lean body mass (LBM) is everything in your body that isn't fat: muscle, bones, organs, skin and water. It drives your metabolism and your strength, and for health it matters more than the number on the scale.
Four formulas compared
- Body fat %: the most accurate if you know your body fat, because it is simply your weight minus your fat mass.
- Boer: a well-validated formula based on height and weight. It is the default when body fat is unknown.
- James and Hume: older formulas, shown for comparison.
Don't know your body fat? Get an estimate with the Body Fat Calculator and enter it here for a more accurate result.
Why LBM is a better target than weight
Two people can weigh the same and look completely different. When you lose weight, the goal is to lose fat while keeping, or even building, lean mass. That means:
- strength training 3–4 times a week, with progressive overload;
- eating enough protein (about 1.6–2.2 g per kg; your LBM-based target is shown above);
- avoiding very large calorie deficits;
- sleeping 7–9 hours.
Re-check your LBM every 6–8 weeks. If your lean mass holds steady or rises while your weight drops, your plan is working.
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