Body Fat Percentage Calculator

How to use this tool

Select sex and units. Choose male or female and your preferred unit system.
Measure and enter circumferences. Measure height, waist (men at navel level; women at the narrowest torso point), neck, and (for women) hips at the widest part of the buttocks.
Enter optional weight. Provide your body weight to see lean body mass and fat mass in addition to the percentage.
View results. Your body fat percentage and ACE classification are displayed instantly.

How the US Navy method works

The US Navy body fat formula estimates body fat percentage from circumference measurements - no scale required. The formula uses logarithms to relate the ratio of waist-to-neck (and for women, waist+hip-to-neck) circumferences to body fat:

Men: BF% = 495 ÷ (1.0324 − 0.19077 × log₁₀(waist−neck) + 0.15456 × log₁₀(height)) − 450
Women: BF% = 495 ÷ (1.29579 − 0.35004 × log₁₀(waist+hip−neck) + 0.22100 × log₁₀(height)) − 450

Body fat classifications (ACE)

The American Council on Exercise defines the following ranges:

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

How to take accurate measurements

Measurement technique significantly affects accuracy. Measure after a normal exhale, keep the tape level where indicated, and do not flex or pull the tape tight enough to compress the skin.

Men's waist: measure horizontally at navel level, at the end of a normal exhale.
Women's waist: measure horizontally at the narrowest point of the torso, at the end of a normal exhale.
Neck: measure just below the larynx (Adam's apple), with the tape sloping slightly downward at the front. Keep your neck relaxed.
Hips (women only): measure horizontally around the widest point of the buttocks.
Take each measurement twice and average the results if they differ by more than 0.5 cm.

Method comparison

Method	Equipment needed	Typical accuracy	Notes
US Navy (circumference)	Tape measure	±3–5 percentage points	Free, no scale needed; less accurate for very muscular or obese individuals
BMI-derived estimate	Scale, height measure	±5–8%	Very rough; does not distinguish fat from muscle
Skinfold calipers	Calipers (low cost)	±3–5%	Technique-dependent; most accurate in trained hands
Bioelectrical impedance (BIA)	BIA scale or handheld	±3–8%	Affected by hydration; convenient for tracking trends
DEXA scan	Clinical scanner	±1–2%	Gold standard; also measures bone density; costs $50–$150 at clinics

Frequently asked questions

How accurate is the US Navy method?

The US Navy circumference method is an estimate that can differ from DEXA (dual-energy X-ray absorptiometry) by several percentage points. Accuracy depends on consistent tape placement and individual body shape, so use it as a general estimate rather than a diagnosis.

Where exactly should I measure?

For men, measure the waist horizontally at navel level; for women, measure at the narrowest point of the torso. Measure the neck just below the larynx (Adam's apple), with the tape sloping slightly downward at the front. Women should also measure the hips around the widest part of the buttocks. Keep the tape level where indicated and measure after a normal exhale without flexing.

What is a healthy body fat percentage?

According to the American Council on Exercise (ACE): men - athletes 6–13%, fitness 14–17%, average 18–24%, obese 25%+. Women - athletes 14–20%, fitness 21–24%, average 25–31%, obese 32%+. Essential fat (minimum for survival) is approximately 2–5% for men and 10–13% for women.