How to use this body fat calculator
- Gender — pick male or female. The formula differs, and women also enter a hip measurement.
- Height — your standing height in centimeters.
- Neck — measure just below the larynx (Adam's apple), with the tape sloping slightly down at the front.
- Waist — at the navel for men, or at the narrowest point for women.
- Hip — women only, measured at the widest point around the buttocks.
- Weight — optional. Add it to also see your fat mass and lean mass in kilograms.
The results update instantly as you type. You will see your estimated body fat percentage, a fitness category, and — if you enter your weight — how many kilograms of that is fat versus lean body mass.
How the US Navy method works
The US Navy body fat formula uses the circumference of your neck and waist (and hip for women) together with your height to estimate body fat percentage. Because fat tends to gather around the midsection, the gap between your waist and neck is a surprisingly strong predictor of overall body composition. The math uses base-10 logarithms of those measurements, so small tape errors only nudge the result slightly. It is the same approach the military uses for quick, equipment-free screening, which is why it stays popular for at-home tracking. It works best when you measure the same way each time — same tape, same spots, first thing in the morning — so the trend you see reflects real change rather than measurement noise.
Reading your result
- Essential / Athlete: very lean — typical of competitive athletes.
- Fitness / Average: a healthy, common range for most active adults.
- Above average / Obese: higher body fat that may be worth addressing with diet and exercise.
Frequently asked questions
How accurate is the US Navy body fat method?
For most people it lands within about 3 to 4 percentage points of a DEXA or hydrostatic scan, which is good for a free tape-measure method. Consistency matters more than perfection if you are tracking change over time.
Where do I measure my neck and waist?
Measure your neck just below the larynx, and your waist at the navel for men or at the narrowest point for women. Women also measure the hip at its widest point. Keep the tape level and snug but not compressing the skin.
What is a healthy body fat percentage?
Roughly 14 to 24 percent is typical for men and 21 to 31 percent for women, though athletes run lower. Essential fat is around 2 to 5 percent for men and 10 to 13 percent for women.
Is my data uploaded?
No — every measurement and result stays in your browser and nothing is sent anywhere.
This tool is for general information only and is not medical advice.
Related: BMI Calculator, BMR & Calorie Calculator, TDEE Calculator.