How accurate is the US Navy method?

Generally within ±3% of more rigorous methods like DEXA when measurements are done carefully. Excellent for tracking changes over time.

Why does women’s formula use hips?

Women carry more essential fat in the hip/thigh area, so the hip circumference materially improves the estimate.

What body fat is "healthy"?

For most adults, men 14–24% and women 21–31% are healthy ranges. Athletes typically live below those bands.

Yes. Below 5% in men or 13% in women is essential-fat territory and isn’t sustainable for everyday health — particularly hormonal function in women.

Why doesn’t this match my smart scale?

Bioelectrical impedance scales depend heavily on hydration and time of day. They’re fine for tracking trends but should not be treated as ground truth.

Body measurements · Composition

Body Fat Calculator

Estimate body fat % using clinical-grade formulas.

Your measurements

Sex

Height

Neck circumferenceBelow the larynx

Waist circumferenceAt the navel

Measure with a soft tape, standing relaxed, not pulling in. Repeat 3× and average for precision.

Body fat %

17.0%

0%45%+

Obese

Higher cardiometabolic risk.

Essential fat2–5%

Athletes6–13%

Fitness14–17%

Average18–24%

Obese25%+

Why body fat % matters

Body fat % gives a far richer picture than weight or BMI alone — distinguishing fat mass from lean tissue. It helps athletes calibrate cutting phases, and ordinary adults understand cardiometabolic risk beyond a single bathroom-scale number.

The US Navy method, explained

Originally developed for the US military, this method uses simple tape measurements to estimate body fat %. It’s remarkably accurate (within ±3% of more invasive methods) when measurements are precise.

Men:    86.010·log10(waist − neck) − 70.041·log10(height) + 36.76
Women:  163.205·log10(waist + hip − neck) − 97.684·log10(height) − 78.387

Measure well, get accurate results

Use a flexible (cloth) tape. Measure first thing in the morning, breathing relaxed, without pulling in. Take three measurements at each site and average them.

Category reference

Category	Range	What it means
Essential fat	2–5%	Minimum for survival — not a healthy long-term target.
Athletes	6–13%	Lean and performance-oriented.
Fitness	14–17%	Visibly fit, sustainable for most active people.
Average	18–24%	Typical for healthy non-athletes.
Obese	25%+	Higher cardiometabolic risk.

Limitations & caveats

Estimates only — DEXA, BodPod and underwater weighing are more precise (and more expensive).
Measurement error of 1 cm at the waist can shift the result by ~1.5% body fat.
Not designed for pregnancy or for bodybuilders with extreme musculature.
Skin-fold callipers can be more accurate for very lean athletes but require practice.
Use the same method every time when tracking changes — consistency beats absolute accuracy.
Bioelectrical impedance scales are convenient but vary widely with hydration.