US Navy validated method
No calipers required
Body category included
±3–4% accuracy
Body Composition

Beyond the
scale — know your
body fat

Your weight doesn't tell the full story. Body fat percentage reveals the ratio of fat to lean muscle — the number that truly matters for health and performance.

No calipers needed Male & Female Lean mass calculated
Essential Athletic Fitness Average Obese 2–5% 6–13% 14–17% 18–24% 25%+ Men's ranges shown · Women's ranges are ~8% higher WAIST CIRC. 85 cm BODY FAT 18.4% LEAN MASS 81.6%
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Body Fat Calculator

US Navy circumference method

Sex
Male
Female
Measure horizontally at navel level, tape parallel to floor
Measure just below the larynx (Adam's apple)
Measure at the widest point of hips and buttocks
—%
—
Body fat percentage

Calculated using the US Navy circumference method (Hodgdon & Beckett, 1984). Typical accuracy is ±3–4% versus DEXA scanning. Accuracy depends heavily on careful, consistent measurement technique.

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Body fat categories

Essential fat M: 2–5% · F: 10–13%
Athletic M: 6–13% · F: 14–20%
Fitness M: 14–17% · F: 21–24%
Average M: 18–24% · F: 25–31%
Obese M: 25%+ · F: 32%+

Ranges based on American Council on Exercise (ACE) guidelines. M = Men, F = Women.

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What is body fat percentage?

Body fat percentage is the proportion of your total body weight made up of fat tissue. Unlike BMI, it distinguishes between fat mass and lean mass — muscles, bones, organs, and water — making it a more accurate measure of body composition.

Two people with identical weight and height can have very different body compositions. A trained athlete may have 12% body fat while a sedentary person of the same weight carries 28%. Only body fat percentage captures this difference.

How the US Navy method works

This calculator uses the US Navy circumference method (Hodgdon & Beckett, 1984). For men: height, waist, and neck measurements are used. For women: hip circumference is added. The formula applies logarithms to estimate fat volume relative to total body volume — no calipers or lab equipment required.

Taking accurate measurements

Accuracy depends heavily on measurement technique. Use a flexible, non-stretch tape measure and follow these guidelines carefully.

Waist circumference

Measure horizontally at navel level. Keep the tape parallel to the floor and do not compress the skin or suck in your stomach.

Neck circumference

Measure just below the larynx (Adam's apple), with the tape perpendicular to the neck's long axis. Look straight ahead while measuring.

Hip circumference (women only)

Measure at the widest point of your hips and buttocks, keeping the tape horizontal. Take each measurement twice and average the results.

Frequently asked questions

The US Navy method typically estimates body fat within 3–4 percentage points of DEXA (dual-energy X-ray absorptiometry) scanning, the gold standard for body composition. Accuracy is higher in people of average build and lower for those with unusual body proportions. It is best used to track trends over time rather than determine an exact number.
For general health, the "fitness" or "average" range is associated with the lowest disease risk — roughly 14–24% for men and 21–31% for women. Athletic body fat levels (6–13% for men, 14–20% for women) are associated with peak performance but are not necessary for good health and can be difficult to maintain long-term.
Yes — this is called body recomposition. Simultaneously reducing fat and increasing muscle is possible, particularly for beginners to resistance training, people returning after a break, or those in a slight calorie deficit with high protein intake and strength training. The scale may barely move while your body composition improves significantly.
The most accurate non-invasive methods are DEXA scanning (±1–2%) and hydrostatic underwater weighing (±1–3%). Air displacement plethysmography (the "Bod Pod") is also highly accurate. Skinfold calipers performed by a trained technician can achieve ±3–5%. The US Navy tape method and bioelectrical impedance scales (BIA) are less precise but far more accessible for regular self-monitoring.
For most people, measuring every 4–8 weeks is sufficient. Body fat does not change overnight, and measuring too frequently leads to anxiety over normal daily fluctuations (mostly driven by hydration and measurement technique) rather than actual changes in fat mass. Consistency in measurement conditions — same time of day, same technique — matters more than frequency.