Calculate your lean body mass (LBM) using scientifically validated formulas. Determine your fat-free mass including muscle, bone, organs, and fluids to better understand your body composition.
Lean Body Mass (LBM) is your total body weight minus the weight of your body fat. It includes everything that isn't fat: muscles, bones, organs, connective tissue, and body water. LBM typically accounts for 60% to 90% of your total body weight, depending on your body composition.
While often used interchangeably, there's a subtle difference between LBM and FFM:
Understanding your lean body mass provides valuable insights for health, fitness, and nutrition planning:
LBM is metabolically active tissue that burns calories. Knowing your LBM helps calculate more accurate daily calorie requirements than using total body weight alone.
Protein needs are better calculated based on LBM rather than total weight, especially for individuals with higher body fat percentages.
Monitor changes in LBM to ensure you're losing fat, not muscle, during weight loss. Increasing LBM indicates successful muscle building.
Some medications are dosed based on LBM rather than total body weight for more accurate and safer administration.
This calculator uses two scientifically validated formulas to estimate lean body mass:
Developed by Dr. P. Boer, this formula is widely used in clinical and research settings for its accuracy across diverse populations.
Men: LBM = (0.407 × weight in kg) + (0.267 × height in cm) - 19.2
Women: LBM = (0.252 × weight in kg) + (0.473 × height in cm) - 48.3
The James formula provides an alternative estimation method that may be more accurate for certain body types and populations.
Men: LBM = (1.1 × weight in kg) - 128 × (weight in kg / height in cm)²
Women: LBM = (1.07 × weight in kg) - 148 × (weight in kg / height in cm)²
Both formulas provide estimates with reasonable accuracy for most individuals. For the most precise measurements, consider professional body composition testing methods like DEXA scans.
Building lean body mass requires a strategic approach combining proper training, nutrition, and recovery:
Engage in strength training 3-5 times per week, focusing on compound movements like squats, deadlifts, bench press, and rows. Progressively increase weight, reps, or sets over time to continually challenge your muscles.
Consume 0.7-1g of protein per pound of body weight daily, or 1.6-2.2g per kg. Distribute protein evenly across 3-5 meals for optimal muscle protein synthesis.
To build muscle, consume 200-500 calories above your maintenance level. A moderate surplus minimizes fat gain while supporting muscle growth.
Muscle growth occurs during recovery, not during training. Prioritize 7-9 hours of quality sleep nightly and manage stress levels.
When losing weight, the goal is to lose fat while maintaining as much lean body mass as possible:
Create a deficit of 300-500 calories per day (or 20-25% below maintenance). Larger deficits increase the risk of muscle loss along with fat loss.
Increase protein to 0.8-1.2g per pound of body weight during a deficit. Higher protein intake helps preserve muscle mass and increases satiety.
Maintain your strength training routine during weight loss. This signals your body to preserve muscle tissue even in a calorie deficit.
Aim for 0.5-1% of body weight loss per week. Faster weight loss increases the proportion of muscle lost along with fat.
Include moderate cardio for additional calorie burn, but don't overdo it. Excessive cardio can interfere with recovery and muscle preservation.
Consider 1-2 week diet breaks at maintenance calories every 8-12 weeks. This can help preserve metabolic rate and muscle mass during extended diets.
While formulas provide useful estimates, several professional methods offer more precise body composition analysis:
Considered the gold standard for body composition analysis. DEXA scans provide detailed information about bone density, lean mass, and fat mass distribution throughout your body. Cost: $50-150 per scan.
Based on Archimedes' principle, this method measures body density by comparing weight on land versus underwater. Highly accurate but requires specialized equipment and proper technique. Cost: $50-100 per test.
Similar principle to hydrostatic weighing but uses air displacement instead of water. Quick, comfortable, and accurate. Cost: $40-75 per test.
Sends a weak electrical current through the body to estimate body composition. Accuracy varies greatly based on hydration status and device quality. Professional-grade devices are more accurate than home scales.
LBM percentage varies by gender and fitness level. Men typically have 75-90% LBM, while women have 70-85% LBM. Athletes and very fit individuals tend toward the higher end of these ranges.
Yes, especially for beginners, those returning after a break, or individuals with higher body fat. However, it's challenging and requires optimal training, nutrition (high protein), and adequate recovery. More advanced lifters typically need to focus on one goal at a time.
Beginners can gain 1-2 lbs (0.5-1 kg) of muscle per month with proper training and nutrition. Intermediate lifters may gain 0.5-1 lb per month, while advanced lifters might only gain 0.25-0.5 lb per month. Women typically gain at about half these rates due to lower testosterone levels.
Yes, sarcopenia (age-related muscle loss) typically begins around age 30, with 3-8% loss per decade after 30, accelerating after 60. However, regular resistance training and adequate protein intake can significantly slow or even reverse this process.
For individuals with normal body fat percentages, using total body weight is fine. However, for those with higher body fat (BMI over 30), calculating protein needs based on LBM or goal body weight provides more appropriate recommendations and avoids excessive protein intake.