Lean Body Mass Calculator – Boer, James & Hume Formulas

A lean body mass calculator estimates the weight of your body minus fat — including muscles, bones, organs, blood, and water. It uses your height, weight, and gender to apply validated formulas (Boer, James, and Hume) and returns your estimated fat-free mass in kg and lbs. This calculator is for educational purposes only and does not replace clinical body composition measurement.

Lean body mass includes all non-fat tissue — skeletal muscle, smooth muscle, bone, organs, blood, and water. Muscle mass refers specifically to skeletal muscle only. LBM is therefore always higher than muscle mass alone. For most people, skeletal muscle makes up roughly 40–50% of LBM.

Among the three formulas, the Boer formula is generally considered the most accurate for typical adults. However, all three are estimates derived from population studies and may be less accurate for very lean, very obese, elderly, or pediatric individuals. For clinical precision, DEXA scanning is more reliable.

A typical adult male (175 cm, 80 kg) might have LBM around 60–65 kg. A typical adult female (165 cm, 65 kg) might have LBM around 42–48 kg. These values vary widely based on fitness level, age, diet, and training history. Higher LBM correlates with more muscle mass and metabolic health.

Yes. Sarcopenia — age-related muscle loss — typically starts in a person's mid-30s and accelerates after age 50. Adults can lose 3–8% of muscle mass per decade after 30. Regular resistance training and adequate protein intake are the most effective countermeasures.

Yes. Many sports dietitians recommend basing protein targets on LBM rather than total body weight, especially for individuals with higher body fat. A common evidence-based range is 1.6–2.2 g protein per kg LBM for muscle building or preservation during caloric restriction.

Lean body mass is the primary determinant of Basal Metabolic Rate (BMR). More lean tissue burns more calories at rest because muscle is metabolically active tissue. This is why individuals with higher LBM have higher BMR and can sustain greater calorie intake without gaining fat.

Yes. The calculator supports both metric (kg and cm) and imperial (lbs, feet, and inches) inputs. Unit conversion is applied automatically before the formulas are calculated, so results are consistent regardless of which system you use.

Yes, it provides a useful baseline estimate for athletes. However, athletes often have significantly higher LBM than predicted by height/weight formulas due to above-average muscle development. For competition-level accuracy, DEXA scanning or skinfold measurement with a trained practitioner is preferred.

Yes. Rapid calorie restriction, especially without adequate protein or resistance training, leads to both fat and muscle loss. This is why slow, controlled weight loss combined with high protein intake and strength training is recommended for preserving LBM during a fat-loss phase.

Yes. The formulas used are universal and this calculator supports both metric and imperial units. It is freely accessible and commonly used globally, including India, USA, UK, Canada, Australia, UAE, Germany, Singapore, and more.

General healthy ranges: men 14–20% body fat, women 21–28%. Athletes typically range 6–13% (men) or 14–20% (women). These are broad guidelines — individual health markers and clinical history matter more than hitting a specific number. Body fat below 5% in men or below 12% in women may be physiologically unsustainable.