Mr Calcu | Find out how much of your weight is lean muscle to fuel smarter training and nutrition.

Discover your lean body mass instantly. Boost your training and transform your fitness with this precise, easy-to-use LBM calculator you'll love.

Lean Body Mass Calculator

Metric

Imperial

Weight (kg)

Body Fat Percentage (%)

Lean Body Mass Calculator Guidelines

You’ve got this—just follow these quick steps to get your LBM:

How to Input Your Data

Enter your weight in kilograms or pounds.
Input body fat percentage as a whole number (e.g., use 25 for 25%).
Ensure that your unit system is consistent — don't mix metric and imperial.
Use reliable tools for body fat measurement when possible.

Important Notes

The result is an estimate — different formulas may yield slightly different LBM values.
LBM includes organs, bones, water, and muscles — not just muscle mass.
Very low (below 2%) or high (above 70%) body fat percentages may yield inaccurate results.
Pregnancy, dehydration, or recent illness can distort body composition data.
LBM cannot exceed total body weight.

Edge Cases to Consider

Extreme Athletes: High muscle mass may exceed the model's assumptions — clinical testing is recommended.
Obese Individuals: May need more advanced imaging like DEXA for accurate lean mass.
Very Low Body Fat: Competitive athletes under 5% should use validated lab methods.
Aging Adults: Sarcopenia affects LBM despite stable total weight — monitor regularly.
Adolescents: Growth spurts can alter LBM significantly within short timeframes.

Lean Body Mass Calculator Description

What is Lean Body Mass?

Lean Body Mass (LBM) refers to everything in your body except fat. It includes:

Muscles
Bones
Organs
Body water
Connective tissues

LBM is essential for:

Basal metabolic rate (BMR)
Performance monitoring
Recovery planning
Health assessment

LBM Calculation Methods

1. Body Fat Subtraction Method (Most Common)

LBM = Total Body Weight - (Total Body Weight × Body Fat Percentage ÷ 100)

2. James Formula (for Men)

LBM = (1.10 × Weight) - 128 × (Weight ÷ Height)^2

3. Hume Formula (Gender Specific)

For men:   LBM = 0.32810 × Weight + 0.33929 × Height - 29.5336
For women: LBM = 0.29569 × Weight + 0.41813 × Height - 43.2933

How to Use This Calculator

Select your preferred units: metric (kg, cm) or imperial (lbs, inches).
Enter your total body weight.
Input your estimated or measured body fat percentage.
Receive an estimate of your Lean Body Mass (LBM).

Pro Tip: For best accuracy, use body fat percentage from a DEXA scan, caliper test, or bioelectrical impedance scale.

Take control of your fitness journey—calculate your lean body mass now and unlock smarter training today.

Example Calculation

Example LBM Calculations

Weight	Body Fat %	Lean Body Mass
70 kg	20%	56 kg
154 lbs	20%	123.2 lbs
100 kg	8%	92 kg
90 kg	35%	58.5 kg
120 lbs	12%	105.6 lbs
85 kg	2%	83.3 kg
130 kg	45%	71.5 kg

Frequently Asked Questions

Lean body mass is the total weight of your body excluding fat. It includes bones, muscles, organs, and water.

LBM = Body Weight - (Body Weight × Body Fat Percentage ÷ 100)

Muscle mass is a component of LBM. LBM also includes water, bones, and organs.

No. Since LBM is body weight minus fat, it cannot exceed total body weight.

You can estimate it using visual guides or tools like skinfold calipers, bioelectrical impedance scales, or DEXA scans.

Yes. Dehydration can reduce apparent lean mass since water is a component of LBM.

Yes. Some formulas like Hume and Boer have gender-specific versions to account for physiological differences.

LBM correlates strongly with strength, endurance, and metabolic rate, making it critical for athletic performance and recovery.

The higher your LBM, the more calories your body burns at rest, making LBM crucial in calculating accurate maintenance or deficit caloric intake.

Mr Calcu | Find out how much of your weight is lean muscle to fuel smarter training and nutrition.

Lean Body Mass Calculator

Lean Body Mass Calculator Guidelines

How to Input Your Data

Important Notes

Edge Cases to Consider

Lean Body Mass Calculator Description

What is Lean Body Mass?

LBM Calculation Methods

1. Body Fat Subtraction Method (Most Common)

2. James Formula (for Men)

3. Hume Formula (Gender Specific)

How to Use This Calculator

Example Calculation

Example LBM Calculations

Frequently Asked Questions

What is lean body mass?

How do I calculate LBM?

What’s the difference between LBM and muscle mass?

Can LBM be higher than body weight?

What if my body fat is unknown?

Is LBM affected by hydration levels?

Should women use different formulas?

Why is LBM important for athletes?

How does lean body mass affect calorie needs?

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