How to measure for the U.S. Navy method
Use a flexible tape measure, stand relaxed and don't pull the tape tight enough to compress the skin. Take each measurement two or three times and use the average.
- Height: without shoes, standing straight.
- Neck: just below the larynx (Adam's apple), with the tape sloping slightly downward toward the front.
- Waist: men measure horizontally at the level of the navel; women measure at the narrowest part of the abdomen. Don't suck in your stomach.
- Hips (women only): at the widest point of the buttocks.
U.S. Navy body fat formula
The method was developed by Hodgdon and Beckett at the Naval Health Research Center and is still used by the U.S. military. With measurements in centimeters:
Example: a man who is 178 cm tall with a 38 cm neck and 86 cm waist has an estimated body fat of about 17.2% — in the "fitness" range.
Body fat percentage chart
Categories from the American Council on Exercise (ACE):
| Category | Women | Men |
|---|---|---|
| Essential fat | 10–13% | 2–5% |
| Athletes | 14–20% | 6–13% |
| Fitness | 21–24% | 14–17% |
| Average | 25–31% | 18–24% |
| Obese | 32% and above | 25% and above |
Essential fat is the minimum needed for normal body function. Women naturally carry more essential fat than men for reproductive health.
How accurate is the Navy method?
Circumference methods typically estimate body fat within about 3–4 percentage points of laboratory methods for most people, which is comparable to many bioelectrical impedance scales. Accuracy depends heavily on consistent measuring technique. For tracking progress, the trend over time matters more than any single reading. DEXA scans, hydrostatic weighing and air displacement (Bod Pod) are more precise but cost more.
Fat mass and lean mass
If you enter your weight, the calculator splits it into fat mass (weight × body fat %) and lean body mass (everything else: muscle, bone, organs and water). Lean mass is useful for setting protein targets and for the Katch-McArdle BMR formula.
Frequently asked questions
What is a healthy body fat percentage?
According to ACE, about 14–24% is typical for fit-to-average men and 21–31% for fit-to-average women. Healthy ranges also vary with age, and older adults tend to carry slightly more fat.
How accurate is the U.S. Navy body fat calculator?
For most people it estimates body fat within roughly 3–4 percentage points of lab methods. It can be less accurate for very muscular people or those with unusual fat distribution. Consistent measuring technique improves reliability.
Why does the calculator need my neck measurement?
Neck circumference serves as a proxy for lean mass and frame size. Subtracting it from the waist (and hips for women) helps isolate the fat stored around the abdomen.
Is body fat percentage better than BMI?
Body fat percentage tells you more about body composition, because BMI cannot distinguish muscle from fat. Using both, along with waist size, gives a more complete picture.
How often should I measure my body fat?
Every 2–4 weeks is enough to see meaningful trends. Measure at the same time of day, ideally in the morning before eating, for the most consistent results.
This calculator provides general information only and is not a substitute for professional medical advice, diagnosis or treatment. Always consult a doctor or other qualified health provider about your individual situation.
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