Body fat calculator
Estimate your body fat percentage with nothing but a tape measure — the U.S. Navy circumference method, used on hundreds of thousands of service members.
Measure with a soft tape: neck just below the larynx, waist at the navel. Relaxed, not sucked in.
How the Navy method works
Developed by the Naval Health Research Center, the method predicts body density from circumference measurements — neck and waist for men, with hips added for women — and converts it to a body fat percentage. The logic is simple: the waist tracks fat storage, the neck tracks frame size, and the difference between them carries most of the signal.
Add your weight and the calculator splits it into fat mass and lean mass — the number that matters most when dieting, because a good cut is defined by how much lean mass survives it. Estimates are for healthy adults and aren't medical advice.
Frequently asked questions
How accurate is the Navy body fat method?
Typically within 3–4 percentage points of a DEXA scan — on par with consumer bioimpedance scales and far more consistent day to day, since tape measurements don't swing with hydration the way electrical methods do. Its real strength is tracking: measure the same spots the same way every few weeks and the trend is reliable even if the absolute number is a little off.
How do I take the measurements?
Use a soft measuring tape, snug but not compressing the skin, and stand relaxed — no flexing or sucking in. Neck: just below the larynx, tape sloping slightly downward to the front. Waist: horizontally at the navel. Hips (women): at the widest point. Take each twice and average; measuring in the morning before eating gives the most repeatable numbers.
What's a healthy body fat percentage?
Broadly: for men, 6–13% reads as athlete range, 14–17% fitness, 18–24% average; for women, 14–20% athlete, 21–24% fitness, 25–31% average. Women carry more essential fat by design (about 10–13% versus 2–5% for men), which is physiologically necessary — not something to diet away.
Should I chase a specific body fat number?
Chase the trend, not the number. Every measurement method has error, so the useful signal is whether the percentage is moving in the direction you want over months. Coaches typically pair a tape measurement with progress photos and scale weight — three noisy signals that together tell a clear story.
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