📏 Navy Body Fat Calculator
The US Navy method estimates body fat from a few tape measurements — neck and waist for men, plus hips for women — using your height as a reference.
16.4%
Estimated body fat
Fitness
Category (ACE)
Uses the US Navy circumference (tape) method — measure the neck just below the larynx, the waist at the navel, keeping the tape snug and level. It\'s a quick estimate (typically within a few percent of more precise methods) and body-measurement data stays on your device. Not medical advice — for clinical accuracy, use DEXA or hydrostatic weighing. 🔒 In your browser.
How the navy body fat calculator works
Measure the circumference of your neck and waist (and hips for women) with a tape measure, along with your height. The calculator applies the US Navy (Hodgdon-Beckett) circumference formula, which relates those measurements on a logarithmic scale to body-fat percentage, and places the result in a standard category. All the maths runs in your browser, so your body measurements never leave your device.
Measure with a snug, level tape: the neck just below the larynx, the waist at the navel, and (for women) the hips at their widest point. The Navy method is a convenient estimate — usually within about 3% of more precise methods — but it can be off for very muscular or very lean builds, since it infers fat from girth alone. It is not medical advice; DEXA or hydrostatic weighing give clinical accuracy.
Frequently asked questions
How do I calculate body fat with a tape measure?
Measure your neck and waist (men) or neck, waist and hips (women), plus your height, then enter them here. The US Navy formula converts those circumferences into a body-fat percentage — no scales or calipers needed.
How accurate is the Navy body fat method?
It's typically within about 3 percentage points of methods like DEXA for average builds — good enough for tracking changes over time. It's less accurate for very muscular or very lean people because it estimates fat from body measurements alone.
Where exactly do I measure?
Neck: just below the larynx (Adam's apple), tape sloping slightly down at the front. Waist: at the navel for men, at the narrowest point for women. Hips (women): at the widest point. Keep the tape snug but not compressing the skin.
Is my measurement data private?
Yes — the calculation runs entirely in your browser and nothing is uploaded, so your body measurements stay on your device. It also works offline once loaded.