Body Fat Calculator

Use the US Navy circumference method: measure your neck at its narrowest point and your waist at the navel (women also measure hips at the widest point), then combine them with your height in a logarithmic formula. This calculator does the math instantly — measure with a snug (not tight) tape, directly on skin, for the best result.

It's an estimate. Studies generally find it lands within a few percentage points of lab methods like DEXA for most people, but it can be further off for very muscular, very lean, or very overweight individuals. Treat it as a consistent way to track your trend, not a medical measurement.

Commonly cited fitness ranges (based on the ACE categories) are roughly 14–24% for men and 21–31% for women, with athletes lower and essential fat around 2–5% for men and 10–13% for women. Healthy varies with age, genetics, and goals — talk to a doctor before making big changes.

Yes — free, no sign-up, and everything is calculated in your browser, so your measurements and weight are never uploaded or stored anywhere.