Health & Fitness
Lean Body Mass Calculator
Use this lean body mass calculator to separate total body weight into estimated fat mass and non-fat mass.
Lean body mass
—
- Fat mass
- —
Student quick launch
Grade planning, algebra checks, and formulas students reach for most.
Study path
Use this calculator with
Follow these when you want the formula behind the answer, a short lesson, or nearby tools in the same topic.
What the lean body mass calculator solves
Use this lean body mass calculator to separate total body weight into estimated fat mass and non-fat mass.
Formula
How to use it
- Enter body weight.
- Enter body fat percentage.
- Read lean mass and fat mass.
How to read the answer
Lean body mass includes muscle, bone, organs, water, and other non-fat mass.
Common mistakes and edge cases
- Body fat estimates can be inaccurate.
- Lean mass is not the same as muscle mass.
- Use the same body-fat method when tracking changes.
Worked examples
20 percent body fat
Lean body mass
64 kg
Lower body fat
Lean body mass
59.5 kg
Frequently asked questions
Is lean body mass muscle?+
Not exactly. It includes all non-fat tissues and water.
Why use body fat percentage?+
It lets the calculator split body weight into fat mass and lean mass.
Related calculators
Body Fat Calculator
Estimate body fat percentage using the U.S. Navy circumference method with measurement validation.
Protein Intake Calculator
Estimate daily protein grams from body weight and goal, with calories from protein.
Macro Calculator
Split daily calories into protein, fat, and carbohydrate targets by goal and body weight.
BMI Calculator
Calculate adult BMI from metric or imperial measurements, see CDC-style categories, healthy weight range, and target BMI weight.
BMR Calculator
Estimate basal metabolic rate using the Mifflin-St Jeor equation with clear formula substitution.
Calorie Calculator
Estimate daily maintenance calories from age, sex, height, weight, and activity using BMR and TDEE.
Last updated: May 8, 2026