Body Fat Calculator
Estimate your body fat percentage with the U.S. Navy tape method from a few measurements, plus your fat mass, lean mass, and fitness category.
Body fat percentage is often a more useful measure than weight alone, because it separates fat from muscle, bone, and water. This calculator uses the U.S. Navy circumference method — a tape measure and a few numbers, no special equipment required.
How it works
The Navy method estimates body fat from the ratio of your circumferences (neck and waist, plus hips for women) to your height. Larger waist-to-neck measurements relative to height indicate more fat:
- Men: use neck, waist, and height.
- Women: use neck, waist, hip, and height.
From your body fat percentage and weight, the calculator also splits your weight into fat mass and lean mass (everything that isn’t fat).
Body fat categories
The result is classified using American Council on Exercise (ACE) ranges, which differ by sex because women naturally carry more essential fat:
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
Measuring accurately
The number is only as good as your measurements. Use a flexible tape, keep it level and snug (not tight), and measure at the same time of day. Because the method has a margin of a few percent, it is best used to track change over time rather than to chase a single exact figure.
Frequently asked questions
How accurate is the U.S. Navy body fat method?
For a no-equipment method, it's reasonably good — typically within about 3–4% of a DEXA scan for most people. Accuracy depends on measuring in the right places with a snug (not tight) tape. It's a useful way to track changes over time, even if the absolute number isn't perfect.
What is a healthy body fat percentage?
It differs by sex. For men, roughly 14–24% is considered fitness-to-average and 25%+ is obese. For women, who carry more essential fat, roughly 21–31% is fitness-to-average and 32%+ is obese. Athletes are often below these ranges.
Where do I measure my waist and neck?
Measure your neck just below the larynx, your waist at the navel for men and at the narrowest point for women, and (women) your hips at the widest point. Keep the tape level and snug against the skin without compressing it.