Skinfold Caliper Protocols

The Clinical Standard for Cheap Tracking

Skinfold calipers measure the thickness of subcutaneous fat (fat immediately under the skin) at specific anatomical sites. When performed correctly, caliper testing is highly reliable and significantly more accurate than consumer bioelectrical impedance (BIA) scales.

However, precision requires strict adherence to anatomical landmarks and consistent technique.

Equipment Selection

Do not buy £5 plastic calipers (e.g., standard Accu-Measure). They deform under pressure, rely on a flimsy click-mechanism, and lack the spring tension required for clinical consistency.

You need a Harpenden (the £200 gold standard) or a high-quality Lange or Slimguide (the acceptable £20 alternative). A Slimguide caliper provides constant spring tension of 10g/mm², which is the minimum requirement for accurate Jackson-Pollock equations.

Technique Rules

1. Always measure on the right side of the body. (Standard clinical practice).
2. Pinch the skinfold. Do not pull muscle. If you feel hard tissue, release and pinch shallower.
3. Wait 2 seconds. Apply the caliper 1cm away from your fingers. Wait exactly 2 seconds for the fluid in the fat to compress before reading the dial.
4. Take three rotations. Measure all sites once, then repeat the entire circuit twice more. Take the average of the three readings for each site to eliminate anomalies.

The Jackson-Pollock Protocols

The most validated equations for the general lifting population are the Jackson-Pollock (JP) formulas.

Jackson-Pollock 3-Site (Men)

• Chest: Diagonal fold, halfway between the anterior axillary line (armpit crease) and the nipple.
• Abdomen: Vertical fold, 2cm to the right of the umbilicus (belly button).
• Thigh: Vertical fold on the anterior midline of the thigh, midway between the proximal border of the patella (kneecap) and the inguinal crease (hip).

Jackson-Pollock 3-Site (Women)

• Triceps: Vertical fold on the posterior midline of the upper arm, halfway between the acromion (shoulder) and olecranon processes (elbow).
• Suprailiac: Diagonal fold immediately above the crest of the ilium (hip bone), on the anterior axillary line.
• Thigh: (Same as men).

The 7-Site Expansion

The 7-site method adds the Midaxillary, Subscapular, and Calf to the protocol. While theoretically more accurate, it requires a highly skilled technician. If you are measuring yourself or having an untrained friend do it, stick to the 3-site method; the compounding error of measuring 4 additional sites poorly will yield a worse result.

Common Mistakes

• Testing post-workout: Blood flow to the skin and muscle (hyperemia) swells the tissue, artificially increasing the skinfold thickness.
• Testing while dehydrated: Changes the compressibility of the subcutaneous layer.
• Inconsistent pinching depth: The most common error. The pinch must lift the subcutaneous fat layer entirely away from the underlying muscle fascia.

Use our Jackson-Pollock 3-Fold Tool to calculate your body density and body fat percentage from your raw millimeter data.