Free Body Fat Calculator (US Navy Method)
Quick answer: this free calculator needs no signup. Measure your height, neck and waist (women also measure hips) and enter them below. The US Navy formula estimates your body fat percentage from those numbers. It is an estimate, usually within a few percentage points, so use it to track change over time rather than as a single verdict.
Free and private, no signup: your numbers stay in your browser. Also free to start: the Calorie Planner, Diet Builder and Workout Generator.
Body fat ranges
American Council on Exercise categories. Women sit higher because essential fat supports hormonal and reproductive function.
| Category | Men | Women |
|---|---|---|
| Essential fat | 2 to 5% | 10 to 13% |
| Athletes | 6 to 13% | 14 to 20% |
| Fitness | 14 to 17% | 21 to 24% |
| Average | 18 to 24% | 25 to 31% |
| Above average | 25% and over | 32% and over |
How the US Navy method works
The formula was developed for the US Navy (Hodgdon and Beckett, Naval Health Research Center, 1984). It uses the difference between waist and neck circumference, scaled by height, because that difference tracks how much fat sits around the middle. For women it adds hips. It needs only a tape measure, which is why it is useful at home.
How to measure properly
- Stand relaxed and measure on bare skin, breathing out normally.
- Neck: just below the larynx, tape sloping slightly down at the front.
- Waist: at the navel for men, at the narrowest point for women. Do not pull the tape tight.
- Hips (women): around the widest point of the buttocks.
- Measure twice and use the average. Repeat at the same time of day.
What this number cannot tell you
It does not measure where fat sits or how much lean mass you carry, and it can read high or low if you carry a lot of muscle or are older. For fat mass, lean mass and recomposition analysis, use the Body Composition tool. To turn a body fat goal into calories, use the TDEE calculator. The performance tools hub has the rest.
Track it over time, free to start. The AadiFit app stores your measurements and adjusts training and nutrition as your numbers change. Start with the free assessment.
Body fat calculator questions
How do I calculate body fat percentage with a tape measure?
Measure your height, your neck just below the larynx, and your waist at the navel (women also measure hips at the widest point). The US Navy formula turns the waist-minus-neck difference and your height into a body fat estimate. This calculator does the maths for you.
How accurate is the US Navy body fat method?
It is an estimate, not a lab measurement. It was developed by the US Navy for people who cannot get DEXA or underwater weighing, and it can be off by several percentage points for individuals, especially very lean, very muscular or older people. Measure the same way, at the same time of day, and watch the trend rather than a single reading.
What is a healthy body fat percentage?
Using the American Council on Exercise ranges: for men, 14 to 17 percent is fitness and 18 to 24 percent is average; for women, 21 to 24 percent is fitness and 25 to 31 percent is average. Essential fat is about 2 to 5 percent for men and 10 to 13 percent for women, and going lower than that is unsafe.
Why is the body fat range higher for women?
Women carry more essential fat for hormonal and reproductive function, so the same health range sits several points higher than for men. Compare yourself to the ranges for your sex, not to a number from a man.
Is body fat percentage better than BMI?
It answers a different question. BMI only uses height and weight, so it cannot tell muscle from fat. Body fat percentage separates fat mass from lean mass, which is more useful for tracking fat loss or muscle gain. Neither is a diagnosis.
What should I do with my result?
Use it as a baseline and re-measure every two to four weeks. To turn it into a calorie target, use the TDEE calculator. To see fat mass, lean mass and recomposition analysis, use the Body Composition tool.
Sources: Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center reports 84-29 and 84-11, 1984. Category ranges: American Council on Exercise. Educational tool, not medical advice.
