Body Fat Calculator

Calculate body fat percentage using US Navy method

About Body Fat Calculator

This calculator estimates body fat percentage using the US Navy method, which uses body circumference measurements (neck, waist, and for women, hips) along with height. It's a widely used, tape-measure-only alternative to calipers or DEXA scans.

Formula

Men: %BF = 495 / (1.0324 − 0.19077×log10(waist−neck) + 0.15456×log10(height)) − 450 | Women: adds hip measurement to the formula

How It Works

Enter your height, neck circumference, and waist circumference (and hip circumference if female)
Measure at the navel for waist, just below the Adam's apple for neck, and at the widest point for hips
The calculator applies the US Navy circumference formula for your sex
Result shows estimated body fat percentage and a general category (essential, athletic, fitness, average, obese)

Tips

Measure consistently — same time of day, same tape tension, same landmarks — for accurate tracking over time
The US Navy method is an estimate; it can be less accurate for people with atypical body compositions (very muscular or very tall/short)
Track trends over weeks rather than relying on a single measurement, since normal fluctuations (hydration, food) can shift results

Frequently Asked Questions

How accurate is the US Navy body fat method?

It's generally within 3-4% of more precise methods like DEXA scans for most people, making it a reasonably accurate and accessible option, though less precise for very muscular or unusually shaped individuals.

What is a healthy body fat percentage?

Ranges vary by sex and fitness level, but general categories are roughly: essential fat 2-5% (men) / 10-13% (women), athletes 6-13% (men) / 14-20% (women), fitness 14-17% (men) / 21-24% (women), and average 18-24% (men) / 25-31% (women).

Why does the formula need different measurements for men and women?

Men and women tend to store fat differently (more around the abdomen for men, more around the hips for women), so the formula includes hip circumference for women to account for this pattern.

Where exactly do I measure my waist and neck?

Measure waist at the navel level, and neck just below the larynx (Adam's apple), keeping the tape horizontal and snug but not compressing the skin.

Is this more accurate than a BMI calculation?

Yes, for estimating actual body composition — BMI only uses height and weight and can't distinguish muscle from fat, while circumference-based methods approximate fat percentage directly.