Body Fat Percentage
WEBEstimate your body fat percentage with the US Navy method.
Enter your height, neck and waist (plus hip for women) to estimate your body fat.
The U.S. Navy method is an estimate for general guidance, not medical advice. For a precise reading, talk to a health professional.
What is the Body Fat Percentage tool?
This body fat percentage calculator uses the U.S. Navy circumference method to estimate how much of your weight is fat, from a few simple tape measurements — no calipers, scales or scans needed. You enter your height, neck and waist (plus hip for women), and the calculator returns your body fat percentage and the fitness category it falls into, from essential fat through athletic, fitness and average to obese.
The Navy method is popular because it is quick and needs only a soft tape measure. For men it works from waist minus neck; for women it adds the hip measurement, which is why the female formula asks for one more number. Because the category bands differ between men and women, you pick your sex first and the tool applies the right formula and the right thresholds automatically. You can switch between centimetres and inches with one tap.
Everything runs entirely on your device: measurements are processed client-side in your browser, nothing is uploaded, and no account is needed — body composition is exactly the kind of personal data that should never touch a server. It is free and works on your phone. One honest caveat: the Navy tape method is an estimate that tends to land within a few percentage points of a DEXA scan for most people, but measurement technique matters and it is less accurate at the extremes. Treat the number as a useful trend line to track over time, not a clinical diagnosis, and talk to a health professional about what it means for you.
How to use the Body Fat Percentage
- Pick metric (cm) or imperial (in) units.
- Choose your sex — this sets the formula and the category thresholds.
- Measure and enter your height, neck and waist (women also enter hip circumference).
- Read your estimated body fat percentage and its fitness category — it updates instantly.
- Re-measure every few weeks and compare to track changes over time.
Frequently asked questions
How is body fat percentage calculated with the Navy method?
For men: %BF = 495 / (1.0324 − 0.19077·log10(waist − neck) + 0.15456·log10(height)) − 450. For women it adds the hip: 495 / (1.29579 − 0.35004·log10(waist + hip − neck) + 0.22100·log10(height)) − 450, with all measurements in centimetres. The calculator converts inches to centimetres for you when you use imperial units.
Where do I measure my neck, waist and hip?
Measure the neck just below the larynx with the tape sloping slightly down at the front. Measure the waist at the navel for men and at the narrowest point for women, and the hip at the widest point of the buttocks. Keep the tape snug but not tight, and don't hold your breath — good technique is the biggest factor in an accurate reading.
What is a healthy body fat percentage?
It differs by sex. For men, roughly 6–13% is athletic, 14–17% fit, 18–24% average, and 25%+ is classed higher. For women, about 14–20% is athletic, 21–24% fit, 25–31% average, and 32%+ higher. Women naturally carry more essential fat than men, which is why the bands are set higher.
How accurate is the U.S. Navy body fat method?
It is an estimate, not a lab measurement. For most people it lands within a few percentage points of a DEXA or hydrostatic reading, but it is less reliable at very low or very high body fat and depends heavily on how carefully you measure. Use it to watch a trend over weeks rather than to fix an exact number.
Is my data private?
Yes. Your measurements are processed entirely in your browser — nothing is uploaded, stored or sent to any server, and no account is needed. Once the page has loaded, the calculator even works offline.
Is this body fat calculator free?
Yes — free, with no sign-up, no account and no limits. Enter your measurements and get your body fat estimate in seconds.