Body Fat Calculator

This tool estimates body fat percentage from circumference measurements using the U.S. Navy circumference method. It requires gender plus height, neck, and waist, and for females also hip. Alongside the percentage it reports a category (Essential / Athletes / Fitness / Average / Obese) and the lean and fat mass derived from the percentage.

1. Select Gender (male or female). 2. Enter Height, Neck, and Waist (and Hip if female) as positive numbers. 3. Click Calculate. 4. Use Reset to clear inputs. Missing fields trigger a 'fill all fields' toast and invalid measurement combinations (e.g. neck >= waist for males) return no result.

Male: %BF = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76. Female: %BF = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387. Results are rounded to 2 decimals and rejected if outside 0–100. Category thresholds — male: <6 Essential, <14 Athletes, <18 Fitness, <25 Average, else Obese; female: <14 Essential, <21 Athletes, <25 Fitness, <32 Average, else Obese.