How the Navy method works
The US Navy method estimates body fat from simple tape measurements and your height. Men use waist and neck; women add hip. It applies a logarithmic formula validated against more expensive methods, and is usually within a few percent of a body-composition scan. A 178 cm man with a 38 cm neck and 85 cm waist comes out around 16%. Everything that is not fat is lean tissue, which the lean body mass calculator quantifies.
How to use this calculator
Set sex (1 male, 0 female), then enter height, neck, and waist in centimetres; women also enter hip. Measure the neck below the larynx, the waist at the navel (men) or narrowest point (women), and the hip at the widest point.
Typical body fat ranges
General reference ranges: essential fat is about 2–5% (men) and 10–13% (women); athletes 6–17% and 14–24%; fitness and average ranges sit higher. Women carry more essential fat than men. These are broad guides, not health verdicts. Where the fat sits matters too, which is what the waist to hip ratio calculator looks at.
Accuracy and limits
Tape methods estimate, they don't measure directly, so technique matters — measure twice and average. For a weight-based screen, see the BMI calculator; for body shape, the BRI calculator. This is for general information only, not medical advice.
Frequently asked questions
- How do I calculate body fat with the Navy method?
- Men use a formula from waist, neck and height; women add hip. Measure with a tape in centimetres and the calculator applies the Navy equations.
- How accurate is the Navy body fat method?
- It's usually within about 3–4% of a body-composition scan when measured carefully, making it a good low-cost estimate.
- What is a healthy body fat percentage?
- Broad reference ranges put fitness levels around 14–17% for men and 21–24% for women, with athletes lower. Ranges vary by source and age.
- Why do women need a hip measurement?
- Women's body-fat distribution differs, so the Navy formula for women includes hip circumference for a better estimate.
- Should I measure before or after eating?
- Measure first thing in the morning, before eating or drinking. A full stomach or bloating can add a centimetre or two at the waist, and that is enough to shift the estimate by a percentage point.