How accurate is a body fat calculator compared to a DEXA scan?

Circumference-based methods like the Navy formula have a larger margin of error than clinical methods like DEXA, often several percentage points, but are useful for tracking personal trends over time with consistent measurement technique.

Why does body fat calculation use different formulas for men and women?

Men and women naturally carry and distribute body fat differently, so formulas like the US Navy method use different measurement sites and calculations calibrated separately for each.

What is essential fat?

The minimum body fat percentage needed for basic physiological function, commonly cited as roughly 2-5% for men and 10-13% for women — going below this range is associated with health risks.

Body Fat Calculator

Estimate your body fat percentage using the US Navy circumference method.

Sex

Units

Height (inches)

Weight (lbs)

Neck Circumference (inches)

Waist Circumference (inches)

Hip Circumference (inches)

Body Fat Reference Chart

Category	Men	Women
Essential Fat	2–5%	10–13%
Athletes	6–13%	14–20%
Fitness	14–17%	21–24%
Acceptable	18–24%	25–31%
Obese	25%+	32%+

Source: American Council on Exercise (ACE)

How to use

Select your sex — females need an additional hip measurement.
Measure your neck just below the larynx (Adam's apple), sloping slightly downward.
Measure your waist at the narrowest point (males) or navel level (females).
Measure your hips (females only) at the widest point.
Use a flexible tape measure and measure in the morning for consistency.
The US Navy formula uses logarithms of circumference measurements.
Results are estimates — individual body composition varies.

About this Body Fat Calculator

Body fat percentage estimates what portion of total body weight is fat versus lean mass (muscle, bone, organs, water). Unlike BMI, which only uses height and weight, body fat estimates typically use circumference measurements to account for body composition differences that weight alone can't capture.

Common estimation methods

US Navy method: uses neck, waist, and (for women) hip circumference measurements alongside height, a widely used formula for reasonably quick self-measurement
Skinfold calipers: measure skin thickness at several body sites, requiring some technique to get consistent results
Bioelectrical impedance: used by many smart scales, estimates fat based on how an electrical signal passes through the body's tissue
DEXA scan: the clinical gold standard, but requires specialized medical equipment, not something available for at-home use

Why these are estimates, not precise measurements

Circumference-based formulas like the Navy method are convenient but have a real margin of error (often cited as several percentage points) compared to clinical methods like DEXA. They're most useful for tracking a personal trend over time — consistent measurement technique matters more than the absolute number for that purpose.

General body fat percentage ranges

Healthy ranges differ by sex and vary by source, but commonly cited ranges are roughly 10–20% for athletic men and 18–28% for athletic women, with "essential fat" minimums (the amount needed for basic physiological function) around 2–5% for men and 10–13% for women.