Use this guide to locate and measure the seven skinfold sites used by Jackson–Pollock body-fat equations.
Calipers measure the thickness of a fold containing skin and subcutaneous fat. An equation uses selected sites to estimate body density and body-fat percentage. Skinfold testing does not directly measure visceral fat.
The male 3-site equation uses chest, abdomen, and thigh. The female 3-site equation uses triceps, suprailiac, and thigh. Both 7-site equations use chest, midaxillary, triceps, subscapular, abdomen, suprailiac, and thigh. Seven sites provide a more detailed protocol, but do not guarantee a more accurate result when site location or technique is inconsistent.
Take at least two readings at each site and rotate through sites rather than repeatedly compressing one fold. The equation needs one final value per site; repeated readings are part of the collection protocol, not a requirement of the equation itself. If a future protocol uses three readings, record the median:
Location and fold: Take a diagonal fold between the front armpit crease and nipple area. Traditional male and female protocols position the site at somewhat different fractions along that line; follow the location specified for the exact protocol you are using and measure the chest-wall fold rather than breast tissue.
Position: Stand relaxed with the arm at the side. Avoid: drifting into the armpit or taking breast tissue.
Location and fold: Take a vertical fold on the midaxillary line—the straight line down the middle of the side of the torso—level with the bottom of the sternum (the xiphoid area).
Position: Stand upright; briefly move the arm only as needed to access the side. Avoid: measuring too far toward the chest or back.
Location and fold: Take a vertical fold on the back of the upper arm, midway between the shoulder and elbow landmarks.
Position: Let the arm hang relaxed. Avoid: flexing the triceps or measuring toward either side of the arm.
Location and fold: Take a diagonal fold just below the lower tip of the shoulder blade, following the natural angle of the fold.
Position: Stand relaxed with arms at the sides. Avoid: placing the site directly over the shoulder blade.
Location and fold: Take a vertical fold approximately 2 cm to the right of the navel.
Position: Stand relaxed without pulling in the abdomen. Avoid: measuring through the navel or changing the offset between sessions.
Location and fold: Take a diagonal fold immediately above the iliac crest—the upper edge of the hip bone—aligned with the natural fold.
Position: Stand relaxed with the arm moved only if needed. Avoid: measuring on the side of the waist without first locating the hip-bone edge.
Location and fold: Take a vertical fold on the front of the thigh, midway between the hip crease and the top of the kneecap.
Position: Keep the measured leg relaxed and shift weight to the other leg when practical. Avoid: flexing the thigh or selecting the midpoint by eye without locating both landmarks.
Choose a repeat schedule that is useful for your goals and allow enough time to observe a trend rather than reacting to small reading differences. Technique consistency is more useful for progress tracking than frequent measurements taken under changing conditions.
Results depend on site location, pinch technique, caliper quality, hydration, tissue compressibility, the measurer, and how closely the person matches the source equation. An estimate may differ from DEXA, hydrostatic weighing, bioelectrical impedance, or other methods. Consistently collected readings are often most useful for following trends. Results are informational and are not medical advice or a diagnosis.
No. The equation requires one final measurement for each site. At least two readings help check consistency; three readings may be summarized with the median when your chosen protocol calls for it.
Some sites are accessible, but hard-to-reach sites are better measured by another person who can maintain the correct location and fold direction.
Keeping the measurer, calipers, time of day, landmarks, and protocol consistent reduces avoidable variation when comparing trends.