Work out body fat (skinfold 3 site) instantly with clear inputs, formula shown and shareable results.
The Jackson-Pollock three-site equation predicts body density from the sum of chest, abdomen and thigh folds for men (or triceps, suprailiac and thigh for women) plus age, then converts density to fat percentage with the Siri equation. A 37 mm sum at age 30 gives a density near 1.0709 and about 12.3% fat.
Jackson-Pollock 3-site density
D = 1.10938 - 0.0008267 x sum + 0.0000016 x sum^2 - 0.0002574 x age
Siri conversion
%fat = 495 / D - 450
These figures are population-average estimates, not a medical assessment or diagnosis. Body composition equations carry errors of several percentage points, and healthy ranges vary with age, ethnicity, muscularity and medical history. Discuss weight or body composition goals with a qualified clinician or dietitian.
Because a given amount of subcutaneous fat corresponds to more internal fat as people age, so the same folds imply higher total fat.
Very. Take three readings at each site, use the median, and always pinch the same anatomical landmark - technique dominates the error.