Body Fat Calculator
Estimate your body-fat percentage with the US Navy tape method - no calipers. Just three measurements (four for women) and your height.
How it works
The US Navy method estimates body fat from circumference measurements and your height, using a logarithmic regression:
Men: %BF = 495 / (1.0324 − 0.19077·log₁₀(waist − neck) + 0.15456·log₁₀(height)) − 450Women: %BF = 495 / (1.29579 − 0.35004·log₁₀(waist + hip − neck) + 0.22100·log₁₀(height)) − 450
We compute in metric to avoid rounding loss; if you enter inches we convert internally. Enter your bodyweight to also get fat mass and lean mass.
Worked example
A man at 180cm with a 38cm neck and 85cm waist: waist − neck = 47 → about 16% body fat - in the "fitness" range.
Frequently asked questions
How accurate is the Navy method?
Usually within 3–4% of a DEXA scan - less precise than calipers or DEXA, but free and repeatable at home. Its strength is tracking change: measure consistently and the trend matters more than any single reading.
How and where do I measure?
Flexible tape, snug but not compressing. Neck: below the larynx. Waist: at the navel (men) or narrowest point (women). Hip (women): widest point. Relaxed, bare skin, measure twice.
Why do women also measure the hip?
Women's fat distribution differs, so the female formula adds hip circumference to model it. Without the hip, the female estimate would be unreliable.
Centimetres or inches?
Either - toggle the unit. The math is the same; just stay consistent so your tracked trend is comparable.
Absolute numbers or trends?
Track the trend. No field method is a perfect absolute, but measured the same way each time, the direction and rate of change are accurate and actionable.