Skinfold Body-Fat Assessment

Skinfold measurement estimates percent body fat from the thickness of subcutaneous fat at standardized sites, assuming a predictable relationship between subcutaneous and total body fat. It is the most widely used field body-composition method. Full measurement technique lives in skinfold-measurement; accuracy/sources of error in skinfold-accuracy.

Protocol summary: use calibrated calipers; grasp a fold ~1 cm from the marked site, measure ~1–2 s after releasing the caliper trigger; take 2–3 measurements per site (within ~1–2 mm) on the right side. Sum the sites and apply a population-specific equation:

• Jackson-Pollock 3-site — men: chest, abdomen, thigh; women: triceps, suprailiac, thigh.
• Jackson-Pollock 7-site — adds subscapular, midaxillary, and others. The summed skinfolds yield body density, converted to %fat (e.g., Siri equation: %fat = (495 / Db) − 450).

Accuracy: typically ±3.5% of the true value with a skilled tester and the right equation — better than BIA, not as good as DEXA/hydrostatic. Tester skill and site consistency are the dominant error sources; the same tester should perform re-tests.

• Estimates %body fat from summed standardized skinfolds via a regression equation.
• Common equations: Jackson-Pollock 3-site and 7-site (site sets differ by sex).
• Body density → %fat via Siri (%fat = 495/Db − 450) or Brozek.
• Accuracy ~±3.5% with a skilled tester; tester/site consistency dominate error.
• Right side, 2–3 reps/site; same tester for re-tests.

• skinfold-measurement — full site-by-site technique.
• skinfold-accuracy — error sources and validity.
• body-composition-overview — where skinfolds sit among methods.
• bia / dexa — alternative methods.