Your body fat percentage tells you far more about your fitness than weight alone. This body fat calculator uses the U.S. Navy circumference method — a validated formula that estimates body fat from simple tape measurements, no calipers, scales or lab equipment required.
How the U.S. Navy method works
Developed by the Naval Health Research Center (Hodgdon & Beckett), the method estimates body fat from the circumference of your neck and waist (plus hips for women) together with your height. The women's formula adds the hip measurement because fat distribution differs. Enter each measurement in centimeters or inches — every field has its own unit switch.
How to measure correctly
Accuracy depends on measuring at the right spots with a snug, level tape: the neck just below the larynx (Adam's apple), the waist at the navel for men or the narrowest point for women, and the hips at the widest point (women). Measure directly on skin, relax, and don't pull the tape tight.
What the result means
The calculator shows your estimated percentage, a category, and where you fall on the spectrum. As a guide (ACE categories): essential fat is 2–5% for men and 10–13% for women; athletes typically sit around 6–13% / 14–20%; fitness 14–17% / 21–24%; average 18–24% / 25–31%; and above that is classed as high. Women naturally carry more essential fat than men.
How accurate is it?
For most people the Navy method lands within 3–4% of clinical methods such as DEXA scans — remarkably good for a tape measure. Very muscular or very lean physiques can deviate more. For tracking progress, consistency matters more than absolute precision: measure at the same time of day, the same way, every few weeks. Pair it with the BMI calculator and calorie calculator to build a fuller picture.
For general information only — not medical advice.