Body Fat Calculator

This uses the US Navy circumference method: neck and waist (plus hips for women) against height. Done carefully, it lands within ±3–4% of lab methods — genuinely useful, genuinely imperfect.

Every consumer method (smart scales, handheld devices, this tape method) has error bars. The practical move is to measure the same way, same time of day, and watch the trend across weeks rather than obsessing over any single number.