Health & Fitness calculator
Lean Body Mass Calculator
Estimate your lean body mass and fat mass.
About the lean body mass calculator
The lean body mass calculator estimates your fat-free mass using body fat percentage from the US Navy method.
How to use this calculator
- 1
Enter body details
Enter weight, height, waist, neck, and gender.
- 2
View results
See your lean body mass, fat mass, and body fat percentage.
How the calculation works
Calculates body fat % using the US Navy method, then lean mass = weight × (1 − body fat %).
Example: 80 kg, 20% body fat: 64 kg lean mass, 16 kg fat mass.
Important health disclaimers
These calculators provide estimates based on population averages. Individual results vary based on genetics, body composition, medical conditions, and medications. Always consult a healthcare provider before starting a new diet or exercise program, especially if you have underlying health conditions.
Understanding body composition metrics
BMI doesn't distinguish muscle from fat. Body fat % is more accurate but depends on measurement technique. TDEE varies day-to-day based on activity. Macro targets are starting points — adjust based on your results, energy levels, and goals. Hydration needs increase with exercise, heat, and altitude.
Important limitations
This tool provides a mathematical estimate based only on the values entered. It does not account for regulations, taxes, lender fees, market conditions, or individual circumstances. Results are for planning purposes only — consult a qualified professional for regulated, medical, financial, or construction decisions.
Frequently asked questions about lean body mass calculator
How accurate is the lean body mass calculator?+
The calculation follows the displayed formula and retains full numeric precision before formatting the result.
Can I use the result professionally?+
Use it as a planning estimate. Confirm regulated, medical, financial, or construction decisions with a qualified professional.