How much muscle do you have? This free muscle mass calculator estimates your skeletal muscle mass from height, weight, age and sex, with its percentage of body weight and your lean mass for context.
Your details
cm
kg
ftin
lb
yrs
This estimates skeletal muscle mass from height, weight, age and sex using a published anthropometric equation. It’s an approximation, not a body-composition scan.
Estimated skeletal muscle mass
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Fill in your details
% of body weight
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Lean body mass
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Per height² (SMI)
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Method
Lee (2000)
An estimate only — formulas can’t see your real composition. Methods like DEXA or BIA are far more accurate. Healthy muscle mass varies widely by build, training and genetics.
Use this free muscle mass calculator to estimate your skeletal muscle mass from your height, weight, age and sex. See your estimated muscle mass, its share of body weight, and your lean body mass for context.
What this muscle mass calculator shows you
A muscle mass calculator estimates your skeletal muscle mass — the muscle attached to your skeleton that moves your body — using a published anthropometric equation. It shows the estimate in weight, as a percentage of body weight, and alongside your lean body mass and a muscle index (SMI).
How muscle mass is estimated
This tool uses the Lee (2000) equation, which estimates skeletal muscle mass from height, weight, age and sex. For a 30-year-old man at 75 kg and 178 cm, it estimates roughly 32–33 kg of muscle — around 43% of body weight. Women typically have a lower share, reflecting natural differences in body composition.
Muscle mass vs lean body mass
Term
What it includes
Skeletal muscle mass
The muscles that move your body.
Lean body mass
Everything that isn’t fat — muscle plus bone, organs and water.
SMI
Muscle mass divided by height squared, used to compare across body sizes.
So lean body mass is always larger than muscle mass — the calculator shows both so you don’t confuse them.
How to use the muscle mass calculator
Select your sex and units.
Enter your height, weight and age.
Read your estimate, with percentage, lean mass and SMI.
Why muscle mass matters
Strength and mobility rely on healthy muscle.
Metabolism — muscle burns more energy at rest than fat.
Healthy ageing — maintaining muscle helps protect against frailty.
Context for weight — two people of the same weight can differ greatly in muscle.
Muscle Mass FAQ
How do I calculate my muscle mass?
This calculator uses the Lee (2000) anthropometric equation, estimating skeletal muscle mass from your height, weight, age and sex. It's an approximation, not a body-composition scan.
How much muscle mass should I have?
It varies widely by build, sex, training and genetics. Skeletal muscle is often roughly 30–45% of body weight, typically higher in men. There's no single "right" number — trends over time matter more.
What's the difference between muscle mass and lean body mass?
Muscle mass is just the muscle; lean body mass is everything that isn't fat — muscle plus bone, organs and water. Lean mass is always the larger figure, and the calculator shows both.
How accurate is the estimate?
It's a reasonable approximation from simple inputs, but it can't see your real composition. DEXA scans and bioelectrical impedance (BIA) are far more accurate.
How can I build muscle mass?
Regular resistance training with progressive overload, enough protein, and adequate rest are the main drivers. A coach or professional can tailor a plan to you.
Is the muscle mass calculator free to use?
Yes, this muscle mass calculator is completely free, needs no sign-up, and gives instant results in your browser.
