Skinfold Body Fat (7-Site) Calculator

About this calculator

The Jackson-Pollock 7-site skinfold method estimates body density by measuring skinfold thickness with calipers at seven standardized points — chest, midaxillary, triceps, subscapular, abdomen, suprailiac and thigh — then plugging the sum into a regression equation that differs for men and women and adjusts for age. That body density is then converted to a body fat percentage using the Siri equation, a widely used formula relating density to fat mass.

Personal trainers, strength coaches and athletes favor the 7-site method over simpler 3-site protocols or bioelectrical impedance scales because measuring more sites reduces the error introduced by any single inaccurate pinch, giving a more reproducible estimate for tracking body composition changes over weeks or months of training. It remains an estimate — actual accuracy depends heavily on measurement technique and caliper consistency — but it is inexpensive and far more informative than BMI, which cannot distinguish muscle from fat.

This calculator takes your seven skinfold measurements, age and sex, and returns your estimated body density and body fat percentage.