Enter your height, neck, and waist measurements to see your estimate.
Your estimated body fat
0–0%
- Category
- –
- Method accuracy
- ≈ ±3.5 percentage points
This is a circumference-based estimate for generally healthy adults, not a substitute for a clinical body-composition measurement (like DEXA) or medical advice.
Body Fat Percentage Estimator
This calculator estimates body fat percentage using the U.S. Navy circumference method — a tape-measure-based technique that needs no scale, calipers, or scanning equipment. It’s not as precise as a clinical method like DEXA, but it’s free, quick, and reasonably consistent for tracking change over time.
What is the U.S. Navy method?
Developed by the Naval Health Research Center in the 1980s as a practical field alternative to skinfold calipers, the method estimates body fat from just a few circumference measurements — neck and waist for men, with hip added for women — combined with height. It was validated against hydrostatic (underwater) weighing, one of the more accurate body-composition methods available at the time.
How this calculator works
Circumferences are converted to centimeters, then plugged into a formula that differs by sex, since body fat tends to be distributed differently between men and women:
- Men: uses neck, waist, and height.
- Women: uses neck, waist, hip, and height.
The result is shown as a range centered on the calculated estimate, reflecting the method’s typical accuracy of about ±3.5 percentage points compared to more precise lab methods — treating the estimate as exact would overstate how precise a tape measurement can really be.
How to measure accurately
- Neck: just below the larynx (Adam’s apple), tape level, snug but not compressing the skin.
- Waist (men): at the navel.
- Waist (women): at the narrowest point of the natural waist.
- Hip (women): at the widest point around the hips and glutes.
- Measure without clothing over the tape line, standing relaxed, and take each measurement two or three times to make sure the numbers are consistent.
Body fat percentage categories
These commonly cited category ranges (based on American Council on Exercise classifications) can help put a number in context:
- Men: Essential fat 2–5% · Athletes 6–13% · Fitness 14–17% · Average 18–24% · Obese 25%+
- Women: Essential fat 10–13% · Athletes 14–20% · Fitness 21–24% · Average 25–31% · Obese 32%+
“Essential fat” is the minimum your body needs for normal hormonal and organ function — it isn’t a target to fall below, particularly for women, whose essential fat range is notably higher than men’s.
How accurate is this method?
Compared to DEXA scanning (a common clinical reference standard), the Navy circumference method is generally reported to be accurate within about 3–4 percentage points for most people, though accuracy can decrease at the extremes of body size or for people with atypical fat distribution. It’s a solid tool for tracking your own trend over time, but two different people’s single readings aren’t precise enough to reliably rank who has “more” or “less” body fat when the numbers are close.
Frequently asked questions
Is the Navy method as accurate as DEXA or calipers?
No single field method matches a clinical scan for precision, but the Navy method compares reasonably well to other accessible options like skinfold calipers, without requiring any special equipment or training to use consistently.
Why do men and women use different formulas?
Body fat tends to be distributed differently by sex — women typically carry more of it in the hips, so the female formula adds a hip measurement that isn’t part of the male version.
Why is my result shown as a range?
A single decimal number would imply more precision than a tape measurement can actually deliver. The range reflects the method’s typical margin of error against more precise lab measurements.
Can I use this to track progress over time?
Yes — that’s one of its best uses. Because the same method and measurement technique are applied consistently, changes in your number over weeks or months tend to be more meaningful than any single reading in isolation.
What if my result seems too high or too low?
Double-check that each measurement follows the instructions above (tape level, correct landmark, no clothing underneath). Small measurement errors, especially at the waist, can shift the result noticeably.
Medical disclaimer
This calculator provides a general, evidence-informed estimate for generally healthy adults. It is not a medical device, and its output is not a diagnosis or a substitute for a clinical body-composition assessment. If you have concerns about your body composition or weight, talk to a doctor or registered dietitian.
Sources & references
- 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, 1984. apps.dtic.mil/sti/citations/ADA143726
- American Council on Exercise. Body fat percentage categories. acefitness.org
- National Institutes of Health. Body composition measurement methods. niddk.nih.gov