All you need is a tape measure. Measure your neck, waist and, for women, hips, then enter them with your height to estimate your body fat percentage.
Body fat calculator
Body fat
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This calculator gives a general estimate for adults and is not medical advice. Talk to a doctor or a registered dietitian before making health decisions.
How it works
This is the circumference method used by the US Navy. It estimates body fat from how waist and neck size relate to height, and is usually within 3–4 percentage points of laboratory methods.
Neck: just below the larynx, tape sloping slightly down to the front.
Waist: men at the navel; women at the narrowest point.
Hips (women): at the widest point of the buttocks.
Measure on bare skin, relaxed, without pulling the tape tight.
Categories follow the American Council on Exercise: for men, 2–5% essential, 6–13% athletes, 14–17% fitness, 18–24% average and 25% or more obesity; for women, 10–13%, 14–20%, 21–24%, 25–31% and 32% or more.
Common questions
How accurate is the Navy method?
It is reasonably accurate for most people but less so for very muscular or very lean bodies. Measure the same way each time to track change.
Why is the weight optional?
The percentage only needs measurements. Weight is used to split your body into fat mass and lean mass.