Measure waist circumference (at the midpoint between the bottom of the rib cage and the top of the hip bone)
Measure height (in the same unit system as waist)
Measure neck circumference (at the midpoint of the neck)
Measure hip circumference (for women: at the widest point of the hips)
Measure body weight (optional for some calculators)
Use the U.S. Navy method:
Men: Body Fat % = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76
Women: Body Fat % = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387
Use a skinfold method (if trained or using a validated protocol):
Take skinfold measurements at standardized sites
Enter measurements into a validated equation (e.g., Jackson–Pollock, Durnin–Womersley) for your sex and age group
Convert estimated body density to body fat % using the corresponding density-to-fat equation for the chosen method
Use a bioelectrical impedance scale (BIA):
Follow the manufacturer’s steps for hydration, timing, and posture
Record the body fat % the device outputs
Use DEXA (most accurate among common consumer methods):
Use the DEXA-provided body fat % directly
Use circumferences with other validated models (if available):
Enter required measurements into the specific validated formula for your sex/age range
Use the formula’s output as your body fat %
Ensure measurement consistency:
Measure at the same times of day
Use the same measuring tape tension and location landmarks
Use the same units (log formulas require consistent units)
Repeat measurements and average if needed