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Lean Body Mass Calculator

Estimate your LBM using the Boer Formula

Enter your details to estimate your lean body mass and body fat percentage.

Your Results

Enter your weight and height to see your estimated lean body mass and body fat percentage.

Understanding Lean Body Mass (LBM)

What is Lean Body Mass?

Lean Body Mass (LBM) is the total weight of your body minus the weight of your body fat. It is essentially everything in your body that isn't fat. This includes:

  • Skeletal Muscle: The muscles you use for movement and strength.
  • Bones: Your skeletal structure.
  • Organs: Heart, lungs, liver, kidneys, etc.
  • Water: Intracellular and extracellular fluids.
  • Connective Tissue: Ligaments, tendons, and skin.

LBM is a critical metric for athletes and fitness enthusiasts because it represents the "functional" part of the body that performs work and burns calories.

The Boer Formula

Our calculator uses the Boer Formula, which is one of the most accurate mathematical models for estimating LBM in adults. It was developed to provide a reliable estimate without the need for expensive clinical equipment like DEXA scans or hydrostatic weighing.

The formulas are as follows:

For Men: $LBM = 0.407 \times weight(kg) + 0.267 \times height(cm) - 19.2$

For Women: $LBM = 0.252 \times weight(kg) + 0.473 \times height(cm) - 48.3$

Why LBM Matters for Your Health

Knowing your LBM is often more useful than just knowing your total weight or BMI. Here is why:

  1. Metabolic Rate: Muscle tissue is metabolically active, meaning it burns more calories at rest than fat tissue. Increasing your LBM increases your Basal Metabolic Rate (BMR).
  2. Strength and Performance: LBM is directly related to your physical strength and athletic performance.
  3. Aging: As we age, we naturally lose muscle mass (sarcopenia). Tracking LBM can help you ensure you are maintaining enough muscle for mobility and health.
  4. Weight Loss Quality: When losing weight, the goal is usually to lose fat while preserving LBM. Tracking LBM helps you ensure your diet and exercise plan are working correctly.

LBM vs. Body Fat Percentage

While LBM tells you how much "non-fat" mass you have, body fat percentage tells you what portion of your total weight is fat. Both are important. For example, two people might weigh 80kg, but one might have 70kg of LBM (very muscular) while the other has 60kg of LBM (higher fat percentage). Their health risks and nutritional needs would be very different.

How to Increase Your Lean Body Mass

  • Resistance Training: Lifting weights or doing bodyweight exercises is the most effective way to build muscle.
  • Protein Intake: Ensure you are eating enough protein to support muscle repair and growth. Aim for 1.6g to 2.2g of protein per kg of body weight.
  • Caloric Balance: To build significant muscle, you usually need a slight caloric surplus.
  • Rest and Recovery: Muscles grow while you sleep, not while you are at the gym. Aim for 7-9 hours of quality sleep.

Frequently Asked Questions

No, but they are related. Muscle mass is a *part* of Lean Body Mass. LBM also includes your bones, organs, and water. However, when people talk about "gaining lean mass," they are usually referring to gaining muscle.

The Boer formula is a statistical estimate. It is very accurate for the "average" person but may be less accurate for extreme outliers, such as professional bodybuilders (who have much more muscle than the formula expects) or the morbidly obese.

Yes, if you lose weight too quickly or don't eat enough protein/do resistance training, your body may burn muscle for energy. The goal of a healthy weight loss plan is to minimize LBM loss.

Quick Tips

  • Eat 0.8g-1g of protein per lb of body weight.
  • Prioritize compound lifts (squats, deadlifts).
  • Stay hydrated; muscles are ~75% water.
  • Track your LBM monthly, not daily.
  • Consistency is key to building lean mass.

Important Links

All Health Calculators Body Fat Calculator Protein Calculator BMR Calculator Macro Calculator

Related Tools

BMI Calculator Ideal Weight Finder Daily Calorie Needs
Learn More

Body Composition & Fitness Resources:

Medical Disclaimer

This Lean Body Mass Calculator is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. LBM estimates can be influenced by many factors including hydration levels and muscle density. Always consult with a qualified healthcare provider or certified fitness professional before making significant changes to your diet or exercise routine.