Body Fat (Tape)
Estimate your body-fat percentage with nothing but a tape measure. Enter height, neck and waist (plus hips for women) to get the U.S. Navy circumference result instantly, privately in your browser.
How to measure
- Height: barefoot, standing straight.
- Neck: just below the larynx (Adam’s apple), tape level.
- Waist: at navel level, relaxed — not sucked in.
- Hip (women): around the widest point.
All measurements in centimetres. Results update instantly and stay on your device.
Formula and source
Men: 495 ÷ (1.0324 ? 0.19077 × log10(waist ? neck) + 0.15456 × log10(height)) ? 450. Women: 495 ÷ (1.29579 ? 0.35004 × log10(waist + hip ? neck) + 0.221 × log10(height)) ? 450, all in centimetres. Source: Hodgdon & Beckett (1984), U.S. Navy circumference method — DTIC ADA370117. Last verified 2026-10-10.
Worked examples
- Man, 178 cm, neck 38 cm, waist 85 cm ? about 16.4{d22ed4253049e3f8ac8a2476ba66be74662354cd56801a0460dd56fc19902ca9} body fat.
- Woman, 162 cm, neck 34 cm, waist 82 cm, hip 97 cm ? about 31.7{d22ed4253049e3f8ac8a2476ba66be74662354cd56801a0460dd56fc19902ca9} body fat.
Accuracy note
This is an estimate, not a medical measurement: expect a typical error of a few percentage points versus lab methods like DEXA, and larger errors for very muscular people, children, or unusual body shapes. For decisions about health, talk to a clinician.
Tips
- Measure in the morning, before eating, for consistent readings.
- Keep the tape level and snug without compressing the skin.
FAQ
How accurate is the Navy body-fat method?
Typically within a few percentage points of lab methods for average adults; less reliable for athletes, children, or unusual builds.
Why does it ask for my neck?
Neck size estimates lean mass, which the formula subtracts from the waist measurement.
Do I need my weight?
No u2014 this method uses only tape measurements and height.
Centimetres or inches?
Enter centimetres. The published equation is calibrated in centimetres.
Is the body-fat calculator free?
Yes, completely free with no signup.
Is my data stored?
No. All calculations happen locally in your browser.