Body Fat Calculator: US Navy Body Fat Percentage Estimate

Body Fat Calculator (US Navy Circumference Method)

Estimate body-fat percentage from height and circumference measurements. The tool uses the US Navy circumference equations; it is an estimate, not a diagnosis or a substitute for a clinician’s assessment.

Measure height and circumferences in the same unit. For the male equation, measure waist at the navel; for the female equation, measure waist at its narrowest point and hips at their widest point. Keep the tape level and snug without compressing skin. Re-enter measurements after changing units; the unit selector converts entered values.

Formula used

The calculator converts inches to centimeters (1 in = 2.54 cm), then applies the metric US Navy circumference equation. Let log₁₀ be the base-10 logarithm:

  • Male equation: body fat % = 495 ÷ [1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)] − 450.
  • Female equation: body fat % = 495 ÷ [1.29579 − 0.35004 × log₁₀(waist + hip − neck) + 0.22100 × log₁₀(height)] − 450.

All dimensions in the equations are centimeters. The equations are empirical estimates and may differ from results from other methods, devices, or clinical measurements.

Worked examples

Male equation: height 180 cm, neck 40 cm, waist 90 cm. The calculation returns about 18.4% body fat.

Female equation: height 165 cm, neck 34 cm, waist 80 cm, hips 100 cm. The calculation returns about 31.4% body fat.

Limits and interpretation

Use adult measurements only. Enter positive, realistic measurements in one consistent unit system. The male equation requires waist greater than neck; the female equation requires waist plus hips greater than neck. If the result seems implausible, check tape placement and units. This estimate does not determine health status, fitness, or an appropriate body-fat target; different methods are not directly interchangeable.

Related calculator

BMI Calculator estimates body mass index from height and weight. BMI and circumference-based body-fat estimates are different measures and should not be treated as interchangeable.