Lean Body Mass Calculator
Estimate your lean body mass — everything that isn't fat.
The non-fat part of you
Lean body mass is everything in your body that is not fat — muscle, bone, organs, water. This estimates it from your weight and body fat, giving a figure that is useful for understanding body composition and that some nutrition and training calculations are based on.
Enter your weight and body fat to estimate lean body mass.
Why lean mass is worth knowing
Lean body mass matters because it is closely tied to metabolism — more lean mass generally means a higher resting energy use — and because preserving it is important, especially when losing weight, where the aim is to lose fat while keeping muscle. Some protein and calorie estimates are based on lean mass rather than total weight, since it better reflects metabolically active tissue. The estimate is only as good as the body-fat figure it is derived from, which is itself approximate, so treat it as a guide. This is general information, not medical or nutrition advice; a qualified professional can help interpret body composition in the context of your goals and health.
Questions & answers
What is lean body mass?
Everything in your body that is not fat — muscle, bone, organs and water. It is estimated from your weight and body fat percentage.
Why does it matter?
It is tied to metabolism and worth preserving, especially when losing weight, where the aim is to lose fat while keeping muscle.
Is this medical advice?
No — it is general information, and only as accurate as the body-fat estimate behind it. A qualified professional can interpret it for you.