Lean Body Mass Calculator
Estimate your lean mass and understand your body composition.
Your Lean Body Mass Estimate
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LBM: 0.0% of total weight
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What Is Lean Body Mass (LBM)?
If you've ever wondered, "what is lean body mass?," you're in the right place. Lean Body Mass (LBM) is the total weight of your body minus all the fat mass. This means your LBM includes the weight of your bones, muscles, organs, skin, and water. Using a lean body mass calculator is an excellent way to get an estimate of this important health metric.
Tracking your LBM is often more useful than tracking your total body weight alone. A standard scale doesn't know the difference between a pound of fat and a pound of muscle. By using this LBM calculator, you can monitor your body composition and ensure that your diet and exercise plan is helping you lose fat while preserving or building valuable muscle.
How to Calculate Lean Body Mass with the LBM Formula
Our body composition calculator provides several methods to estimate your LBM. The most accurate way is by using a known body fat percentage, but if you don't have that, you can use a height and weight-based LBM formula.
- Boer, James, and Hume Formulas: These are scientific formulas that estimate LBM using your height, weight, and sex. They are a great starting point for anyone looking to calculate lean body mass.
- Calculation from Body Fat Percentage: This is the most direct way to find your LBM. If you know your body fat percentage, our calculator will simply subtract your fat mass from your total weight. You can learn more about assessing body composition from research published in the National Library of Medicine.
This tool serves as both a lean body mass calculator for women and a lean body mass calculator for men, using formulas validated for both sexes.
Lean Body Mass vs. Fat-Free Mass (FFM)
You might hear the terms Lean Body Mass (LBM) and Fat-Free Mass (FFM) used interchangeably. While very similar, there is a small technical difference:
- Fat-Free Mass (FFM): Literally everything in your body that is not fat.
- Lean Body Mass (LBM): Includes all your fat-free mass PLUS essential fat. Essential fat is a small amount of fat your body needs to function, found in organs and bone marrow.
For most practical purposes in fitness and health, the difference is minor, and the terms are often used to mean the same thing. The estimations from any LBM calculator are generally close to your FFM.
Frequently Asked Questions (FAQ)
What is a normal lean body mass range?
A "normal" LBM varies greatly depending on age, sex, height, and fitness level. A healthy LBM as a percentage of total weight is typically 60-90% for men and 50-80% for women. Athletes often have a higher LBM percentage. For more on this, Healthline provides a good overview.
Which is the most accurate LBM formula?
The most accurate method to calculate lean body mass is using an accurate body fat percentage measurement. If you don't have one, the Boer formula is often considered a reliable estimation for the general population.
How can I increase my lean body mass?
Increasing LBM means building muscle. The two most important factors are progressive resistance training (lifting weights and consistently challenging your muscles) and consuming enough protein and calories to support muscle growth. A structured workout plan is key to effectively how to increase lean body mass.