Lean Body Mass Calculator

Unit System Gender Height

Weight

Results

Formula	Lean Body Mass	Body Fat
Boer	—	—
James	—	—
Hume	—	—

Lean Body Mass: What It Is, Why It Matters, and how to calculate lean body mass

Lean Body Mass (LBM) is one of the most important indicators of overall health and physical fitness. Unlike body weight alone, lean body mass focuses on the weight of everything in your body except fat, giving a clearer picture of your true body composition. Understanding lean body mass can help you make smarter decisions about nutrition, exercise, and long-term health.
This guide explains what lean body mass is, why it matters, how it affects your metabolism, and the most accurate ways to calculate it.

What Is Lean Body Mass?

Lean body mass refers to the total weight of your body excluding fat mass. It includes:
Muscles
Bones
Organs
Water
Connective tissues
In simple terms:
Lean Body Mass = Total Body Weight − Body Fat Weight
For most healthy adults, lean body mass accounts for 60–90% of total body weight, depending on age, gender, and fitness level.

infographic for Lean body mass Calculator showing muscles, bones, organs, and water as components of lean mass, with a comparison chart illustrating lean body mass versus body fat percentage for health and fitness understanding.

Why Lean Body Mass Is Important for Health

1.Supports a Healthy Metabolism
Lean body mass is metabolically active, meaning it burns calories even at rest. The more lean mass you have, the higher your Basal Metabolic Rate (BMR), making weight management easier.
2. Improves Strength and Physical Performance
Muscle mass plays a vital role in strength, endurance, balance, and mobility. Higher lean body mass helps reduce fatigue and improves athletic performance.
3. Protects Against Age-Related Muscle Loss
As people age, they naturally lose muscle in a process called sarcopenia. Maintaining lean body mass helps preserve independence and reduces the risk of falls and injuries.
4. Enhances Overall Health
Healthy lean mass supports:
Better insulin sensitivity
Stronger immune function
Improved bone density
Lower risk of chronic diseases

How Lean Body Mass Is Calculated?

Lean body mass can be estimated using several scientific formulas. These formulas rely on height, weight, and gender to provide reliable approximations.
Common Lean Body Mass Formulas
1. Boer Formula
Widely used for adults and considered accurate for general populations.
Men:
LBM = 0.407 × weight + 0.267 × height − 19.2
Women:
LBM = 0.252 × weight + 0.473 × height − 48.3
2. James Formula
Often used in medical and pharmacological contexts.
Men:
LBM = 1.1 × weight − 128 × (weight ÷ height)²
Women:
LBM = 1.07 × weight − 148 × (weight ÷ height)²
3. Hume Formula
Commonly used in clinical assessments.
Men:
LBM = 0.32810 × weight + 0.33929 × height − 29.5336
Women:
LBM = 0.29569 × weight + 0.41813 × height − 43.2933
Your lean body mass calculator compares multiple formulas to provide a well-rounded estimate.

What Is a Healthy Lean Body Mass?

There is no single “perfect” lean body mass number, as it depends on:
Height
Gender
Age
Activity level
Instead of chasing a specific value, focus on increasing muscle mass, maintaining strength, and keeping body fat within healthy ranges.

Final Thoughts

Lean body mass is a powerful indicator of health, strength, and metabolic efficiency. Unlike body weight alone, it reveals what your body is truly made of and how well it functions. Whether your goal is fat loss, muscle gain, or overall wellness, understanding and tracking lean body mass can help you make smarter, healthier choices.
Use your lean body mass calculator regularly to monitor progress and stay on track toward a stronger, healthier body.