How to Estimate Body Fat with the US Navy Method
Learn how the US Navy method estimates body fat from height, neck and waist, how to measure correctly, and how to read the result.
Body fat percentage says more about your shape than weight alone. You do not need special equipment to estimate it. The free Body Fat Calculator uses the US Navy method, which needs only a tape measure.
Quick answer
Measure height, neck and waist (and hips for women), enter them in centimetres and read the estimate. A man of 175 cm with a 38 cm neck and an 85 cm waist comes to about 17 percent.
The Body Fat Calculator tool on shobfree.com, ready to use in your browser.
How to measure
- Stand relaxed and measure in the morning, before eating.
- Neck: just below the larynx, tape level, not pulled tight.
- Waist: at the navel for men, at the narrowest point for women.
- Hips (women): at the widest point of the buttocks.
- Take each measure twice and use the average.
How to read the result
Typical ranges for men are about 14 to 17 percent for fitness and 18 to 24 for average. For women, 21 to 24 is fitness and 25 to 31 is average. The tool also shows fat mass and lean mass if you enter your weight.
How accurate is it?
It is an estimate, usually within a few percentage points of more advanced methods. The error can be larger for very muscular or very thin people. Use it to follow your own trend over weeks, with the same measuring habits each time.
Using the number well
- Compare the result with your waist and energy, not just the figure.
- Do not chase very low values. Some fat is essential for health.
- Combine it with the BMI Calculator and Waist-Hip Ratio Calculator for a fuller picture.
Why waist, not weight, tells the story
Two people can weigh the same and look completely different. One may carry more muscle, another more fat around the waist. Fat stored around the stomach is linked with a higher risk of diabetes and heart disease. This is why the Navy method relies on waist and neck, which change as fat changes, rather than on weight alone.
A realistic way to improve the number
Lowering body fat by 1 percent usually takes several weeks of steady habits: walking daily, enough protein, fewer sugary drinks and strength work two or three times a week. Crash diets lose muscle as well as fat and often come back. Track the waist measurement monthly, since it moves more slowly than weight but means more.
Choosing a method
| Method | Pros | Cons |
|---|---|---|
| Tape measure (Navy) | Free, quick, repeatable | Estimate only |
| Skinfold calipers | Cheap, good with practice | Needs technique |
| Bioimpedance scales | Easy at home | Affected by water and food |
| DEXA scan | Very accurate | Costly, needs a clinic |
For tracking at home, the tape method is hard to beat because the only equipment is a tape and you can repeat it every month.
When not to rely on it
If you are pregnant, have an eating disorder, have swelling from illness or are a very high-level athlete, the estimate may be misleading. Ask a health professional for assessment in such cases.
Sources and further reading
- Hodgdon JA, Beckett MB. "Prediction of percent body fat for US Navy men and women from body circumferences and height", Naval Health Research Center, 1984.
Frequently asked questions
How often should I measure? Every two to four weeks is enough.
Is this medical advice? No. Speak to a doctor if you have a health concern.
Can I use it during pregnancy? No. The method is not valid in pregnancy. Ask your doctor for advice.
Next step
Open the Body Fat Calculator and enter your measurements.
