The Diet Body Fat Calculator estimates body-fat percentage from circumference measurements using the U.S. Navy-style logarithmic equations. It can help users track a consistent measurement trend alongside body weight, but it should not be treated as a clinical assessment.
Because tape placement and body shape affect the estimate, repeat measurements under similar conditions and focus on changes over time. The calculator provides separate equations for male and female measurement sets and converts metric inputs internally to inches.
Select the equation that matches the required circumference set.
Stand upright and use centimeters.
Keep the tape level and snug without compressing the skin.
The female measurement equation uses hip circumference.
Repeat under similar conditions and interpret trends cautiously.
Where:
Assumptions: These circumference equations estimate body composition from external measurements and can be biased for some body shapes and populations.
The result is a circumference-based body-fat estimate.
This calculator is not a diagnostic tool and should not be used to judge health from one measurement.
Given:
Calculation:
Convert to inches: height 68.90, neck 14.96, waist 33.46. Body fat = 86.010 × log10(18.50) − 70.041 × log10(68.90) + 36.76 ≈ 16.9%. Fat mass = 75 × 0.169 ≈ 12.7 kg.
Result: About 16.9% body fat and 12.7 kg estimated fat mass.
Small tape-measure differences can materially change the output.
Use the standardized location required by the protocol you follow and use that same location every time.
The underlying formulas use different circumference combinations and constants.
No. It is a field estimate and may differ from imaging or laboratory methods.
True tissue change is slow; short-term differences usually reflect measurement technique or fluid shifts.
No. Discuss body-composition concerns with a qualified professional, especially when health conditions or disordered eating are involved.