Body Fat Calculator — Navy Method & Lean Mass
Enter height, neck and waist (plus hip for the female equation) to see the estimate immediately; optionally add weight for fat mass, lean mass and a target scenario.
Body composition estimate
Independent estimate based on the published U.S. Navy circumference tables; not an official service assessment.
Measurements
Enter the tape measurements below. Your estimate updates immediately.
Optional fat mass and target scenario
Add weight to calculate fat mass, lean mass and a target-weight scenario. These fields do not change the main body-fat estimate.
Where to measure
Body composition
Estimate details
How the calculator works
It evaluates the sex-specific circumference equations behind the tables in the U.S. Navy’s 2021 BCA Guide 4. Metric inputs are converted to inches before the base-10 logarithm formula. This is a continuous estimate and does not reproduce an official rounded service worksheet.
How to measure
Stand relaxed with the tape level and snug. For the male equation, measure the abdomen at the navel and subtract the neck. For the female equation, use the natural waist plus the widest hip, then subtract the neck. Follow the current official procedure if you need a service assessment.
Fat mass and lean mass
With weight entered, fat mass equals weight multiplied by the estimated percentage. Lean mass is the remainder.
Target scenario
Target weight assumes lean mass stays unchanged. Real change can include muscle and water, so this is not a prescription.
Frequently asked questions
Is the Navy circumference method exact?
No. It is a practical field estimate affected by technique, tape placement, and body shape.
Can I use centimeters?
Yes. The calculator converts centimeters to inches internally.
Why does the female equation use hips?
Its circumference value is waist plus hip minus neck; the male equation uses waist minus neck.
Is target weight medical advice?
No. It is a mathematical scenario assuming constant lean mass.
Not the current Army assessment
The U.S. Army replaced its former circumference methods with a waist-to-height ratio assessment in July 2026. Do not use this Navy-style estimate to determine current Army compliance.
