Muscle Mass Calculator
Skeletal muscle mass is a key indicator of physical health and metabolic function. Higher muscle mass is associated with greater strength, better insulin sensitivity, and reduced risk of metabolic disease. This calculator estimates skeletal muscle mass (SMM) using the Lee et al. (2000) anthropometric formula, which has been validated against MRI measurements. The formula uses height, weight, age, sex, and ethnicity to predict muscle mass. Results are shown in kilograms and as a percentage of total body weight. While a DEXA scan or MRI is the gold standard for measuring body composition, this formula provides a clinically validated estimate suitable for health monitoring and goal setting.
Muscle mass formula (Lee et al., 2000)
SMM (kg) = 0.244 x Weight + 7.80 x Height (m) - 0.098 x Age + Sex coefficient + Ethnicity coefficient - 3.3
Sex coefficient: Male = +10.2, Female = 0. Ethnicity adjustments applied as additive corrections. Height must be converted to metres (divide cm by 100).
Muscle mass: frequently asked questions
What is skeletal muscle mass?
Skeletal muscle mass is the total weight of muscles attached to the skeleton that control movement. It is a key component of body composition and is associated with metabolic rate, strength, mobility, and overall health outcomes. Adults typically have 30-50% of body weight as skeletal muscle.
How is muscle mass estimated without a DEXA scan?
Several validated equations estimate skeletal muscle mass from anthropometric measurements. The Lee et al. (2000) formula uses height, weight, age, and sex. While less precise than DEXA or MRI, it provides a useful population-level estimate for health monitoring.
What is a healthy muscle mass percentage?
Healthy skeletal muscle mass as a percentage of body weight is roughly 38-54% for men and 28-39% for women. These ranges decline with age. Athletes typically sit at the higher end, while sedentary older adults may be below healthy ranges (a condition called sarcopenia).
How can I increase muscle mass?
Resistance training (weight lifting, bodyweight exercises) combined with adequate protein intake (1.2-2.0 g per kg of body weight per day, per the Academy of Nutrition and Dietetics) is the most effective approach. Sleep, progressive overload, and consistency are also key.
What is sarcopenia?
Sarcopenia is the age-related loss of muscle mass and function. It typically accelerates after age 50. The European Working Group on Sarcopenia defines it by low muscle mass plus low muscle strength or physical performance. Exercise and protein intake are the primary interventions.
Official sources
- Lee RC et al. (2000): Skeletal muscle mass and aging. Published in the American Journal of Physiology - Endocrinology and Metabolism: PubMed: 10710385.
- National Institute on Aging: Sarcopenia: Loss of Muscle.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.