LeanCheck

Body Fat Calculator

The US Navy method: neck, waist, height (and hip for women) — no caliper required.

Height (cm)

Neck circumference (cm)

Waist circumference (cm)

Estimated body fat

17.3%

US Navy circumference method

What you entered

Gender: MaleHeight: 178 cmNeck: 38 cmWaist: 86 cm

1
Convert measurements to inches
height 178 ÷ 2.54, neck 38 ÷ 2.54, waist 86 ÷ 2.54= 70.1 in, 15.0 in, 33.9 in
2
Waist minus neck
33.9 − 15.0 in= 18.9 in
3
US Navy formula (male)
86.010×log₁₀(18.9) − 70.041×log₁₀(70.1) + 36.76= 17.3%

Result

Estimated body fat: 17.3%

The US Navy method estimates body fat from circumference measurements — it's a reasonable field estimate, but calipers or a DEXA scan are more accurate if precision matters.

Body fat percentage by the US Navy tape method

The US Navy method estimates body fat from height, neck, and waist for men, adding hip for women. Measurements below are in centimetres and are converted to inches internally, which is the unit the formula was derived in.

Sex	Height	Neck	Waist	Hip	Body fat
Male	180 cm	38 cm	85 cm	n/a	16.2%
Male	180 cm	38 cm	95 cm	n/a	23.4%
Male	175 cm	40 cm	90 cm	n/a	19.3%
Female	165 cm	32 cm	75 cm	95 cm	27.7%
Female	170 cm	33 cm	80 cm	100 cm	30.9%

Tape methods carry roughly a 3 to 4 point margin of error against a DEXA scan, and the result is very sensitive to where you place the tape. General wellness information only, not medical advice. Discuss any health decision with a qualified clinician.

Healthy ranges

Adult men: 10–22% is typical, athletes 6–13%. Adult women: 18–30% typical, athletes 14–20%. Below those ranges affects hormones and immunity.

Why body fat matters more than weight

Two people at the same weight can have very different body compositions. A muscular 80 kg person at 12% body fat is healthier than an 80 kg person at 30% body fat. Body fat percentage is a better indicator of metabolic health, disease risk, and physical fitness than BMI or weight alone.

Frequently asked questions

How accurate is the US Navy body fat method?

The US Navy method is accurate to within ±3–4% for most people. It's less accurate for very muscular individuals or those with unusual body proportions. For clinical accuracy, DEXA scans (±1–2%) or hydrostatic weighing are the gold standards.

What is a healthy body fat percentage?

For men: 10–20% is healthy, 6–13% is athletic, below 5% is competition-level and not sustainable. For women: 18–28% is healthy, 14–20% is athletic, below 12% can disrupt hormones. Women naturally carry more essential fat for reproductive health.

How do I measure my waist and neck for this calculator?

Waist: measure at the navel level (or the narrowest point for women), relaxed, not sucking in. Neck: measure just below the larynx (Adam's apple), tape sloping slightly downward at the front. Use a flexible tape measure, snug but not compressing the skin.