Body Fat Percentage Calculator
How it works
This is the U.S. Navy circumference method, fitted separately for each sex against measurements taken with a tape:
Men: 495 / (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450
Women: 495 / (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.221 × log10(height)) − 450
Inches are converted to centimetres once, before any of the arithmetic runs, so the same body gives the same estimate whichever unit was typed.
The category bands below are the American Council on Exercise's reference ranges. They are published as brackets like "14–20%", which is the same thing as "14% up to but not including 21%" — the tables here hold that boundary at the next bracket's start, the way this site's BMI categories do.
Men
| Category | Body fat |
|---|---|
| Essential fat | Under 6% |
| Athletes | 6% to under 14% |
| Fitness | 14% to under 18% |
| Average | 18% to under 25% |
| Obese | 25% and above |
Women
| Category | Body fat |
|---|---|
| Essential fat | Under 14% |
| Athletes | 14% to under 21% |
| Fitness | 21% to under 25% |
| Average | 25% to under 32% |
| Obese | 32% and above |
For weight against height instead of body composition, see the BMI calculator.
Frequently asked questions
How accurate is the tape-measure method?
It is an estimate, not a lab measurement. Compared against DEXA scans or underwater weighing — the methods actually used to measure body composition directly — the Navy circumference method typically lands within a few percentage points, closer for people near an average build and less reliable at the extremes. Treat the number as a reasonable estimate to track over time, not a precise reading.
Why does it need a hip measurement for women but not men?
The male and female versions are two separately-fitted equations, not one formula with a swapped constant. Fat distribution differs enough between the sexes that the regression behind the male formula did not include hip at all, while the one behind the female formula does — that is a property of how each was fitted, not an oversight in one of them.
Is this medical advice?
No. This is a screening estimate from a handful of tape measurements, not a diagnosis or a body-composition assessment. A clinician, or a proper DEXA or hydrostatic scan, is where to go if the number matters for a health decision.