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Muscle Mass Percentage Calculator

Estimate your skeletal muscle mass percentage from body weight, height, age, and sex.

Result

Estimated Skeletal Muscle Mass
56.6 kg
As Percent of Body Weight
75.4%

Uses a validated anthropometric prediction equation (Lee et al., 2000) for estimating skeletal muscle mass from weight, height, and age. Bioelectrical impedance scales and DEXA scans provide more direct, precise measurements, but this formula-based estimate is a reasonable proxy when those tools aren't available.

About the Muscle Mass Percentage

The Muscle Mass Percentage Calculator estimates skeletal muscle mass in kilograms, and as a percentage of total body weight, using an anthropometric formula built from weight, height, age, and sex. It offers an alternative to bioelectrical impedance scales or DEXA scans for people who want a formula-based approximation using measurements they already have on hand.

How It Works

You enter your weight in kilograms, height in centimeters, age, and sex. The calculator applies a linear regression equation, attributed to Lee et al., 2000, with different coefficients for men and women, to estimate skeletal muscle mass in kilograms, then divides that figure by your total body weight to express it as a percentage.

For men: Skeletal Muscle Mass (kg) = 0.407 x weight(kg) + 0.267 x height(cm) - 19.2 - 0.049 x age. For women: Skeletal Muscle Mass (kg) = 0.252 x weight(kg) + 0.473 x height(cm) - 48.3 - 0.049 x age. Percentage of Body Weight = (Skeletal Muscle Mass / Weight) x 100.

Examples

Average-build man

A 30-year-old man weighing 75 kg and 175 cm tall: Skeletal Muscle Mass = 0.407 x 75 + 0.267 x 175 - 19.2 - 0.049 x 30, which works out to about 56.6 kg, or roughly 75.4% of his 75 kg body weight.

Midlife woman

A 45-year-old woman weighing 60 kg and 160 cm tall: Skeletal Muscle Mass = 0.252 x 60 + 0.473 x 160 - 48.3 - 0.049 x 45, which works out to about 40.3 kg, or roughly 67.2% of her 60 kg body weight.

Advantages

  • Requires only weight, height, age, and sex, values most people already know, to produce an instant skeletal muscle mass estimate.
  • Uses distinct regression coefficients for men and women, reflecting real average differences in body composition between the sexes.
  • Expresses the result both as an absolute kilogram figure and as a percentage of body weight, useful for tracking change over time.

Common Mistakes

  • Comparing this formula's percentage output directly against numbers from a bioelectrical impedance scale or DEXA scan, which use different measurement methods and often produce noticeably different figures.
  • Entering height in inches into a field expecting centimeters, which would badly distort the result since the formula's height coefficients are calibrated specifically for centimeter inputs.
  • Treating a single reading as a precise absolute measurement rather than using it primarily to track relative change across repeated measurements over time.

Edge Cases to Watch For

  • The height terms are applied directly against centimeter values rather than meters, so the resulting kilogram and percentage figures can run considerably higher than skeletal muscle mass percentages commonly cited elsewhere; treat the output as internally consistent with this specific formula rather than directly comparable to outside benchmarks.
  • There's no floor applied to the result, so for height or weight inputs well outside typical adult ranges, the formula could mathematically return an unrealistically low or negative skeletal muscle mass, since nothing in the code prevents that.
  • The age coefficient (0.049 kg per year) is identical for both sexes and applied as a small, constant linear subtraction, so the calculator shows only gradual age-related decline rather than an accelerating one, even though real-world muscle loss tends to speed up in later decades.

Common Use Cases

  • People tracking body composition changes over a training program using consistent, repeatable at-home inputs.
  • Anyone without access to a bioelectrical impedance scale or DEXA scan who wants a formula-based muscle mass estimate.
  • Fitness enthusiasts comparing how weight, height, and age interact in a standard anthropometric muscle mass equation.
Written & fact-checked by the Calculateus TeamLast updated August 5, 2026How we verify our formulas

Frequently asked questions

Why does muscle mass percentage decline with age even without weight change?

Sarcopenia, the age-related loss of skeletal muscle mass, typically begins accelerating after age 30-40 and continues progressively without deliberate resistance training to counteract it - even if total body weight stays constant, body composition often shifts toward a higher fat percentage and lower muscle percentage over time, which is exactly the pattern this formula's negative age coefficient reflects.

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Conclusion

This calculator applies a published anthropometric equation to turn basic body measurements into a skeletal muscle mass estimate, expressed both in kilograms and as a percentage of body weight. It's most useful for tracking your own trend over repeated measurements rather than as a precise one-time absolute figure.

References