Body Fat Calculator (US Navy method)

The US Navy method estimates body-fat percent from tape measurements: males use waist minus neck and height; females add the hip measurement — a 175 cm male with 85 cm waist and 38 cm neck is about 16.9%.

Informational only — not medical advice. Consult a qualified professional for personal health decisions.

This calculator implements the US Navy circumference method: an estimate of body-fat percentage from simple tape measurements, developed for large-scale fitness screening. Measure at the navel (waist), below the larynx (neck), and — for females — at the widest hip point, all in centimetres.

Formula & methodology

Males: %BF = 495 ÷ (1.0324 − 0.19077·log₁₀(waist − neck) + 0.15456·log₁₀(height)) − 450

Females: %BF = 495 ÷ (1.29579 − 0.35004·log₁₀(waist + hip − neck) + 0.22100·log₁₀(height)) − 450

Worked examples

Male, 175 cm, waist 85, neck 38 → ≈ 16.9%
Female, 165 cm, waist 80, hip 95, neck 33 → ≈ 29.4%

Limits

A tape estimate is not a clinical body-composition scan (DEXA); expect a few points of error either way, more for very muscular or very lean physiques. Measure at the same time of day with a relaxed tape for consistent tracking.

Frequently asked questions

How accurate is the Navy method?

Studies put it within roughly 3-4 percentage points of laboratory methods for most adults — good for tracking change over time, not for medical decisions.

Where exactly do I measure?

Waist: horizontally at the navel (males) or the narrowest point (females). Neck: just below the larynx, tape sloping slightly down at the front. Hip (females): the widest point.