Body Fat Calculator
Estimate body fat with just a tape measure.
The US Navy body-fat method estimates your body-fat percentage from a few circumference measurements — no calipers or scans needed. It's surprisingly close to lab methods for most people. All you need is a tape measure and two minutes.
How it's calculated
US Navy equations on log10 of circumferences (converted to inches): men use waist, neck and height; women add the hip measurement.
Frequently asked questions
How accurate is the Navy method?
Within about 3–4% of lab methods (like DEXA) for most people — good enough to track trends. Measure consistently: same time of day, same tape tension, no sucking in.
What body-fat percentage is healthy?
Roughly 10–20% for men and 18–28% for women, varying with age. Athletes run lower; going extremely low can disrupt hormones — lower isn't always better.
Why do women need the hip measurement?
The Navy equations were derived separately for each sex because fat distributes differently. For women, the hip circumference is the key extra input that makes the estimate work.