Skeletal Muscle Mass Estimator Formula

Understand the math behind the skeletal muscle mass estimator. Each variable explained with a worked example.

Use the Skeletal Muscle Mass Estimator

Formulas Used

Skeletal Muscle Mass

smm_kg = 0.244 * weight_kg + 7.80 * height_m - 0.098 * age + 6.6 * 1 - 3.3

Skeletal Muscle Mass

smm_lbs = (0.244 * weight_kg + 7.80 * height_m - 0.098 * age + 6.6 * 1 - 3.3) * 2.20462

Muscle % of Body Weight

smm_pct = (0.244 * weight_kg + 7.80 * height_m - 0.098 * age + 6.6 * 1 - 3.3) / weight_kg * 100

Variables

VariableDescriptionDefault
weight_lbsBody Weight(lbs)180
height_inchesHeight(inches)70
ageAge(years)30
height_mDerived value= height_inches * 0.0254calculated
weight_kgDerived value= weight_lbs * 0.453592calculated
bmi_valDerived value= weight_kg / (height_m * height_m)calculated

How It Works

Skeletal Muscle Mass Estimation

SMM (kg) = 0.244 x Weight(kg) + 7.80 x Height(m) - 0.098 x Age + 6.6 x Gender - 3.3

Gender = 1 for male, 0 for female. This calculator uses the male equation.

Typical SMM Ranges (Male)

AgeSMM % of Body Weight 20-2940-44% 30-3937-42% 40-4935-40% 50+30-37%

Worked Example

A 30-year-old male, 180 lbs, 70 inches tall.

weight_lbs = 180height_inches = 70age = 30
  1. 01Weight = 81.6 kg, Height = 1.778 m
  2. 02SMM = 0.244 x 81.6 + 7.80 x 1.778 - 0.098 x 30 + 6.6 - 3.3
  3. 03= 19.9 + 13.9 - 2.9 + 6.6 - 3.3 = 34.2 kg
  4. 04As % = 34.2 / 81.6 x 100 = 41.9%

Frequently Asked Questions

What is skeletal muscle mass?

Skeletal muscle mass is the weight of all voluntary muscles in your body. It is the main contributor to lean body mass and metabolic rate.

How much muscle mass is healthy?

For males aged 20-39, about 40-44% of body weight as skeletal muscle is typical. This naturally decreases with age.

How can I preserve muscle mass?

Resistance training 2-3 times per week, adequate protein intake (0.7-1 g/lb), and sufficient sleep are key to maintaining muscle mass.

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