US Navy Tape Body-Fat Calculator
Use this US Navy tape body-fat calculator to estimate body-fat percentage from your height and tape measurements.
Choose one unit, then measure the abdomen at the navel for the male formula or the natural waist (the narrowest point of your torso) and widest hip for the female formula. Measure your neck around the lower throat, just below the voice box, and repeat the same sites when you compare results.
See your estimated body-fat percentage, compare a small tape-measure difference, and save a baseline. Add your bodyweight for estimated fat mass and fat-free mass, meaning the rest of that bodyweight after the estimated fat mass.
Read your Navy body-fat estimate
Your result is a historical U.S. Navy circumference estimate from height and tape measurements. It is not a body scan or a current service-compliance decision.
If you add bodyweight, the calculator also shows estimated fat mass and fat-free mass based on this result.
Calculate above to see your estimate and the measurements behind it.
Take the tape measurements consistently
Use the same unit and tape sites every time. The male formula uses abdomen at the navel and neck; the female formula uses the narrowest point of the torso, widest hip and neck.
Measure around the lower throat just below the voice box, with the tape level and relaxed. Keep the tape snug without compressing the tissue, and record after a normal breath out.
- Height and tape unit
- Choose inches or centimeters and use it for every tape measurement.
- Formula
- Choose the male or female formula used by this method.
- Bodyweight
- Optional; used for estimated fat mass and fat-free mass. Fat-free mass is the rest of the bodyweight after estimated fat mass.
- Waist comparison range
- A user-chosen scenario showing what a nearby tape reading would do to the estimate.
See how a nearby tape reading changes the estimate
The scenario chart keeps your height, neck, hip and selected formula fixed while changing only the waist input. It shows measurement sensitivity, not a confidence interval or a health range.
The calculator above shows your selected inputs. This table is a worked example of a nearby tape reading.
| Input or result | Value |
|---|---|
| 33.00 in waist | 29.18% (scenario) |
| 33.50 in waist | 29.79% (scenario) |
| 34.00 in waist | 30.39% (observed) |
| 34.50 in waist | 30.99% (scenario) |
| 35.00 in waist | 31.58% (scenario) |
Follow the historical Navy equations
For the male formula, body-fat percentage = 86.010 × log10(abdomen at navel − neck) − 70.041 × log10(height) + 36.76. For the female formula, body-fat percentage = 163.205 × log10(natural waist + hip − neck) − 97.684 × log10(height) − 78.387.
These are the direct published log10 coefficients used by this page. Convert every height and tape measurement to inches before applying the displayed equations. They preserve a historical method and do not establish current service compliance.
See the calculation details
| Input or result | Value |
|---|---|
| Formula | Female |
| Height | 70 in |
| Natural waist | 34 in |
| Neck | 15 in |
| Hip | 40 in |
| Estimated body fat | 30.39% |
| Estimated fat mass | 24.31 kg |
| Estimated fat-free mass | 55.69 kg |
Check a complete example
The illustrative example uses 70 inches of height, a 34-inch natural waist, a 15-inch neck, a 40-inch hip and 80 kg (176.37 lb) of bodyweight with the female formula.
| Input or result | Value |
|---|---|
| Estimated body fat | 30.39% |
| Estimated fat mass | 24.31 kg |
| Estimated fat-free mass | 55.69 kg |
Understand the method limits
This page keeps the historical Navy equation separate from RFM, skinfold, Durnin–Womersley and body-scan methods. A change between methods or a small tape difference does not prove a change in body composition.
The direct-percent coefficients are a historical equation reproduced by the National Academies. They do not determine a current service-compliance result. Use a consistent protocol for a personal baseline and discuss health decisions with a qualified professional.
- National Academies, chapter 5 Medical Factors, p. 118 — institutional reproduction of the direct-percent equation.
- OPNAVINST 6110.1J — historical U.S. Navy policy context.