How the US Navy method works
The US Navy circumference method estimates body fat from the ratio of a few body measurements to your height. For men it uses neck and waist; for women it adds the hip measurement. Because fat and lean tissue are distributed differently, these circumferences correlate well with overall body fat, and the formula converts them into a percentage. It was developed so the Navy could assess personnel without calipers or lab equipment, and it remains popular because anyone with a tape measure can repeat it consistently at home.
Measuring accurately
Accuracy depends entirely on consistent measurements. Measure with a flexible tape, snug but not compressing the skin, first thing in the morning before eating. For the waist, men measure at the navel; women measure at the narrowest point. The neck is measured just below the larynx, and the hip at the widest point. Take each measurement two or three times and average them. Small errors move the result by a percentage point or two, so measure the same way every time — the trend over weeks matters more than any single reading.
What the categories mean
Body fat ranges are sex-specific because women carry more essential fat. For men, roughly 6–13% is athletic, 14–17% is fit, 18–24% is average, and 25%+ is above average. For women the bands sit about 8 points higher: 14–20% athletic, 21–24% fit, 25–31% average, 32%+ above average. Very low body fat is not a health goal for most people — a small amount of fat is essential for hormones and organ protection. Use the category to understand where you sit, not as a target to minimise.
Accuracy and better methods
The Navy method is convenient but approximate, typically within about 3–4% of a lab measurement. It can misjudge very muscular or very lean bodies. For more precision, DEXA scans, hydrostatic weighing and Bod Pod tests are the gold standards, though they cost more and are less repeatable at home. For tracking your own progress, the consistency of the tape method is often more useful than a one-off lab number. These tools use standard, published formulas and the figures you enter. They are estimates for general fitness and planning, not a medical assessment — check with a doctor or dietitian before making health decisions.
Frequently asked questions
How accurate is the US Navy body fat method?
It is usually within about 3–4 percentage points of a DEXA scan for average builds. It is less accurate for very muscular or very lean people, but very consistent for tracking your own trend.
What measurements do I need?
Height and neck and waist for men; women also add the hip. Measure with a snug tape, ideally in the morning, and average two or three readings for each.
What is a healthy body fat percentage?
For men, roughly 10–20% is healthy for most; for women, about 18–28%. Athletes sit lower. A minimum of essential fat (2–5% men, 10–13% women) is needed for health.
Is body fat percentage better than BMI?
For body composition, yes — BMI cannot tell muscle from fat, so a muscular person can read as 'overweight'. Body fat percentage measures the thing you actually care about.