Training estimates

Lean Body Mass Calculator

Calculate your lean body mass and fat mass from total body weight and body fat percentage. Use this Fitness and training tool to enter your numbers, review the result, and understand the key assumptions before making the next decision.

What you get
A focused calculator, clear explanation, common questions, and useful next tools.
Quick intro
Calculator
Result
Explanation
Common questions
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Calculator tool

How this calculator works
The result depends on the numbers you enter and the assumptions shown below.

Lean Body Mass (LBM) is everything in your body except fat — muscles, bones, organs, and water. Knowing your LBM is important for calculating protein needs, tracking fitness progress, and understanding body composition beyond the number on the scale. Fat mass is total weight minus LBM.

Review the inputs carefully and treat the output as an estimate. For decisions involving money, taxes, health, law, or security, compare the result with trusted professional guidance when needed.

Frequently asked questions

Why is lean body mass important?

LBM is the primary driver of metabolic rate and strength. Tracking LBM helps you confirm that weight loss is from fat and not muscle.

How do I find my body fat percentage?

Use a body fat calculator with circumference measurements, skinfold calipers, or a DEXA scan for the most accurate results.

Can LBM be used to set protein targets?

Yes. A common recommendation is 1.6–2.2 g of protein per kg of LBM per day for muscle maintenance and growth.