Body Fat Percentage Calculator

This calculator uses a widely adopted tape-measure formula that estimates body fat from height, neck, waist, and hip circumferences. For men: BF% = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76. For women: BF% = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387. All measurements are converted to cm internally. It is less precise than DEXA scans or hydrostatic weighing but requires only a tape measure and is accurate enough for tracking progress over time.

A healthy body fat percentage depends on your sex and age. For men, a healthy range is roughly 10–20%; for women, 18–28%. Athletes typically fall at the lower end of these ranges. Body fat that is too low is also unhealthy — essential fat (the minimum needed for bodily functions) is about 2–5% for men and 10–13% for women.

Lean body mass (LBM) is the weight of everything in your body except fat — including muscle, bone, organs, and water. It is calculated as: LBM = Total Weight × (1 − Body Fat %). Lean body mass is important for calculating protein requirements, safe weight loss targets, and fitness goals. Preserving lean mass while reducing fat mass is the goal of most body recomposition programs.