The Workout Body Fat Calculator estimates body fat percentage from tape measurements using the U.S. Navy circumference method. It is useful for people who want a repeatable way to track body-composition trends alongside strength, conditioning, or nutrition goals.
Because circumference formulas are population-based estimates, the result is best used as a consistent tracking metric rather than a clinical diagnosis. Measure under similar conditions each time and focus on the direction of change over several weeks.
1. Choose the formula
Select the male or female circumference equation.
2. Enter height
Use standing height without shoes.
3. Measure the neck and waist
Keep the tape level and snug without compressing the skin.
4. Add hip circumference when required
The female equation uses hip circumference.
5. Review the estimate
Compare results taken under the same conditions over time.
Male: Body fat % = 495 / (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450
Female: Body fat % = 495 / (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.22100 × log10(height)) − 450
All circumferences and height are entered in centimeters. The calculator uses base-10 logarithms.
The percentage estimates how much of total body mass is fat tissue.
Tape placement and body shape can materially affect the estimate.
Given: Male, height 175 cm, neck 38 cm, waist 85 cm.
Calculation: 495 ÷ (1.0324 − 0.19077 × log10(47) + 0.15456 × log10(175)) − 450 ≈ 15.5%.
Result: Estimated body fat is about 15.5%.
Different methods use different assumptions. Bioelectrical impedance is influenced by hydration, while circumference methods depend on tape placement and body proportions.
Use a consistent time of day, similar hydration status, and the same tape locations.
Only when using the male equation. The female equation requires a hip measurement.
No. It is a screening-style estimate and does not replace a professional body-composition assessment.
Track the trend over time and pair it with performance, strength, and other health indicators.