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Body Fat Calculator
Your measurements
For women, the hip measurement is needed too. Weight is optional — it is only used to split your result into fat mass and lean mass.
An estimate from the U.S. Navy tape-measure method, usually within about 3–4 percentage points of a DEXA scan. It is not a medical diagnosis.
Example: a man 70 in tall, with a 16 in neck and a 34 in waist, has about 15.5% body fat — the fitness range. At 180 lb, that is 27.9 lb of fat and 152.1 lb of lean mass.
Behind the numbers
How the Navy method works
The U.S. Navy method estimates body fat from a tape measure instead of a scan. It uses the difference between your waist and neck (plus hips for women) and your height in a logarithmic formula developed by Hodgdon and Beckett in 1984. The formula works in centimetres, so inch measurements are converted first (inches × 2.54).
Worked example (man): waist − neck = 86.36 − 40.64 = 45.72 cm and height = 177.80 cm. The denominator works out to 1.0635, so 495 ÷ 1.0635 − 450 = 15.5%. Fat mass is weight × body fat % and lean mass is the rest: 180 × 0.155 = 27.9 lb of fat, 180 − 27.9 = 152.1 lb lean.
Body fat categories
| 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% and over | 32% and over |
A few comparisons
Example results
| Person | Measurements | Body fat | Category |
|---|---|---|---|
| Man | 70 in, neck 16 in, waist 34 in | 15.5% | Fitness |
| Man | 72 in, neck 17 in, waist 38 in | 20.3% | Average |
| Woman | 64 in, neck 13 in, waist 30 in, hips 38 in | 28.9% | Average |
| Woman | 66 in, neck 13 in, waist 27 in, hips 36 in | 21.0% | Fitness |
Measure it right.
Measure in the morning, before eating, standing relaxed — a waist measured after a meal or while sucking in can be an inch or more off.
Take each measurement twice and use the average. If the two readings differ by more than half an inch, take a third.
Measure the waist at the navel for men, and at the narrowest point of the torso for women — the formula was built on those exact spots.
Track the trend, not one number. Re-measure every four weeks under the same conditions; a steady fall matters more than any single reading.
Good to know
Your body fat questions, answered.
How accurate is the Navy body fat method?
It is an estimate with a typical error of about 3 to 4 percentage points compared with a DEXA scan. Tape placement, how hard you pull the tape, and whether you measure after eating all move the result, so treat it as a guide, not a medical measurement.
How is this different from the Army body fat calculator?
Both use a tape measure, but the formulas differ. The Army method (AR 600-9) uses its own logarithmic formula and pass/fail limits by age, while this calculator uses the U.S. Navy (Hodgdon-Beckett) formula, which converts your measurements to centimetres and estimates body density first. The two methods can give results a few points apart for the same person.
How do I measure my waist, neck and hips correctly?
Measure the neck just below the Adam's apple, the waist at the navel for men or the narrowest point for women, and the hips at the widest point. Keep the tape level, snug but not tight, and measure after a normal breath out, standing relaxed.
What body fat percentage is healthy?
For men, 14 to 17% is the fitness range and 18 to 24% is average; for women, 21 to 24% is the fitness range and 25 to 31% is average. Below about 5% for men or 10 to 13% for women is essential fat, the minimum the body needs, and going below it can be unhealthy.