Explains BMI as a screening measure and describes important limitations.
Health & fitness
Lean body mass
Enter your values below for a clear, instant result.
Your result
kg
FormulaLean mass = weight × (1 − body-fat fraction)
- Enter the known values.
- Apply the displayed formula.
- Review the result and supporting values.
Worked example: 70 kg at 20% body fat gives 56 kg lean mass.
Estimate notice: This lean body mass result is an estimate based only on the values and assumptions shown. Verify important decisions with the relevant official source or a qualified professional.
Educational estimate only—not medical advice. Individual health needs vary; consult a qualified clinician when making health decisions.
Understand the result before using it
Lean body mass uses weight and body fat to calculate its result. It uses a population-based health or fitness equation to produce an educational estimate from your measurements.
Formula, assumptions, and example
Formula
Lean mass = weight × (1 − body-fat fraction)
Assumptions
- The entered weight and body fat are complete, valid, and use the units or format shown beside each field.
- Measurements are accurate and were taken using the method expected by the equation.
- Population averages are an acceptable starting point for this educational calculation.
Worked example
70 kg at 20% body fat gives 56 kg lean mass.
When to use it
Good uses
- Understand a general screening measure or planning range.
- Track a consistent estimate over time while using the same method.
- Prepare an informed discussion with a qualified healthcare professional.
Limitations
Common mistakes to avoid
- Individual biology, pregnancy, age, medication, disability, training status, and clinical history may make the estimate unsuitable.
- The result cannot diagnose a condition or prescribe treatment, diet, exercise, or medication.
- Educational estimate only—not medical advice. Individual health needs vary; consult a qualified clinician when making health decisions.
Sources and further reading
These references explain the underlying standards or provide authoritative context. Your own contract, institution, clinician, product documentation, local code, or governing standard may be the controlling source.
Evidence-based context for energy and body-weight planning.
Questions about this calculation
What does the Lean body mass calculate?
Lean body mass uses weight and body fat to calculate its result. It uses a population-based health or fitness equation to produce an educational estimate from your measurements. The formula used is: Lean mass = weight × (1 − body-fat fraction)
Which inputs affect the Lean body mass result?
The result uses weight and body fat. Changing any of these values can change the output, so enter them using the labels and units shown.
Is the Lean body mass result exact?
This lean body mass result is an estimate based only on the values and assumptions shown. Verify important decisions with the relevant official source or a qualified professional.
When should I verify a Lean body mass result?
Verify it before any financial, health, academic, construction, safety, or engineering decision. Use the primary source or an appropriately qualified professional.
Clear answers, without the guesswork
1Enter your information
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2Review the calculation
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