Navy Body Fat Calculator
A man who is 175 cm tall with a 38 cm neck and 90 cm waist estimates at 14.2% body fat with the Navy method used here. This Navy body fat calculator uses the standard US Navy circumference method with sex-specific inputs. Enter height, neck, and waist measurements, then add hip measurement for women. You can use centimeters or inches, and the calculator converts them to the inch-based Navy formula before estimating body fat percentage.
Quick answer
Men use height, neck, and abdomen or waist at the navel.
Use one unit for every field. This calculator converts centimeters to inches before applying the standard Navy formula.
Measure the neck just below the larynx. Men usually measure waist at the navel. Women usually measure waist at the natural waist and hips at the widest point.
What this tells you
- •Men use height, neck, and abdomen or waist at the navel.
- •Women use height, neck, waist, and hip measurements.
- •The calculator accepts centimeters or inches, then converts to inches before applying the standard Navy constants.
- •The result is a body fat estimate, not a diagnosis or a direct scan.
How to Use
- 1Select male or female so the calculator applies the right Navy formula.
- 2Choose centimeters or inches and keep every measurement in that same unit.
- 3Enter height, neck, and waist. If you select female, also enter hip measurement.
- 4Measure with a soft tape, keep it level, and avoid pulling it tight.
- 5Calculate to see your estimated body fat percentage and body density.
How It Works
Formula
Men: Body fat % = 495 / (1.0324 - 0.19077 x log10(waist - neck) + 0.15456 x log10(height)) - 450
Women: Body fat % = 495 / (1.29579 - 0.35004 x log10(waist + hip - neck) + 0.22100 x log10(height)) - 450
All measurements are converted to inches before calculation.This tool uses the standard US Navy circumference equations, often called the Hodgdon-Beckett method. Men use abdomen minus neck with height. Women use waist plus hip minus neck with height. The base-10 logarithm is part of both formulas. Because the constants are tied to inch-based measurements, the calculator converts centimeters to inches first when needed.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
Male example
The calculator converts the measurements to inches, applies the male Navy formula, and returns 14.2% body fat after rounding.
Female example
The female formula uses waist plus hip minus neck, along with height, after converting centimeters to inches. That set of measurements rounds to 18.2% body fat.
How to measure for the Navy body fat formula
Use a soft tape and keep it level against bare skin or thin clothing for more consistent results.
| Measurement | How to measure it | Who needs it |
|---|---|---|
| Height | Stand tall without shoes | Men and women |
| Neck | Measure just below the larynx | Men and women |
| Waist | Men usually measure at the navel. Women usually measure at the natural waist | Men and women |
| Hip | Measure around the widest part of the hips and buttocks | Women only |
The formula needs the male waist measurement to be larger than the neck measurement. For women, waist plus hip must be larger than neck.
Common mistakes
- Mixing centimeters and inches after choosing one unit.
- Measuring over bulky clothing or pulling the tape so tight that the neck or waist shrinks.
- Using a male waist measurement that is smaller than the neck measurement because of a typo or a bad tape position.
- Comparing this estimate as if it were interchangeable with DEXA, calipers, or bioimpedance devices.
Limitations
This Navy body fat calculator gives an adult circumference estimate only. Results can shift with tape placement, posture, breathing, hydration, and body shape. The method may be less accurate for very muscular people, very lean people, pregnant people, and anyone whose body composition falls outside the populations used to build the formula. It is not intended for children.