Calculate your body fat percentage using various methods including Navy, BMI, and measurements.
This calculator estimates body fat percentage with the US Navy circumference method, a tape-measure technique developed by the US Naval Health Research Center. For men, it feeds height, neck, and waist (in centimeters) into the equation 495 / (1.0324 - 0.19077 × log(waist - neck) + 0.15456 × log(height)) - 450. For women, the formula adds the hip measurement: 495 / (1.29579 - 0.35004 × log(waist + hip - neck) + 0.22100 × log(height)) - 450.
Alongside the percentage, the page converts your result into fat mass and lean mass in kilograms, calculates your BMI from height and weight, and places you in a category from Essential to Obese using widely quoted fitness ranges for each sex. The appeal of the method is that it needs nothing more than a flexible tape and two or three careful measurements.
The Navy method is an estimate, not a lab measurement. Accuracy depends heavily on tape placement and tension, and results drift with hydration, meals, and posture. With careful, repeated measurement it typically lands within about 3 to 4 percentage points of hydrostatic weighing or DEXA scans. For a purely height-and-weight view, see our BMI calculator, or compare targets with the ideal weight calculator.
Studies generally find it lands within about 3 to 4 percentage points of laboratory methods such as hydrostatic weighing and DEXA when measurements are taken carefully. That makes it one of the better field techniques that requires no equipment beyond a tape. Its main weakness is measurement error: shifting the tape a centimeter or two can move your result noticeably.
Commonly cited ranges put men at 6 to 13 percent athletic, 14 to 17 percent fit, 18 to 24 percent average, and 25 percent or more obese. For women the bands run roughly ten points higher: 14 to 20 percent athletic, 21 to 24 fit, 25 to 31 average, and 32 or more obese. Essential fat is about 2 to 5 percent for men and 10 to 13 percent for women, and you should never aim below those floors.
Women carry a larger share of body fat around the hips, so the Navy equation for women includes hip circumference alongside waist and neck. Omitting it would systematically skew the estimate. The men's formula leaves the hip term out entirely.
Keep the tape horizontal and snug against the skin without pressing in. Measure the neck just below the Adam's apple, the waist at navel level with muscles relaxed, and the hips at the widest point. Take each measurement two or three times after exhaling normally and use the average.
For most purposes, yes. BMI cannot distinguish a muscular person from an overfat one, while body fat percentage estimates actual composition. That said, the Navy method's accuracy depends on your measuring technique, whereas BMI has the advantage of needing nothing beyond height and weight.