Free Tool
Skinfold Body Fat Calculator
Estimate your body fat percentage using the Jackson-Pollock 3-site skinfold method. Requires a set of body fat calipers.
Diagonal fold halfway between the armpit crease and nipple
Vertical fold 2 cm to the right of the navel
Vertical fold on the front of the thigh, midway between hip and knee
How does the Jackson-Pollock 3-site method work?
The Jackson-Pollock 3-site skinfold method is one of the most widely used and validated body fat estimation techniques in exercise science. Developed by Andrew Jackson and Michael Pollock in 1978, it uses skinfold measurements from three specific body sites to calculate body density, which is then converted to body fat percentage using the Siri equation.
The method uses different measurement sites for men and women. Men are measured at the chest, abdomen, and thigh. Women are measured at the triceps, suprailiac (above the hip bone), and thigh. Age is also factored into the formula because body composition changes as we age.
Measurement sites
For men
- Chest: Diagonal fold halfway between the armpit crease and the nipple
- Abdomen: Vertical fold approximately 2 cm to the right of the navel
- Thigh: Vertical fold on the front of the thigh, midway between the hip and knee
For women
- Triceps: Vertical fold on the back of the upper arm, midway between shoulder and elbow
- Suprailiac: Diagonal fold just above the hip bone (iliac crest)
- Thigh: Vertical fold on the front of the thigh, midway between the hip and knee
The formulas
This method uses a two-step process. First, body density is calculated from the skinfold sum and age:
Men (body density):
1.10938 - (0.0008267 x sum) + (0.0000016 x sum²) - (0.0002574 x age)
Women (body density):
1.0994921 - (0.0009929 x sum) + (0.0000023 x sum²) - (0.0001392 x age)
Siri equation (body fat):
% Body Fat = (495 / body density) - 450
All skinfold measurements are in millimeters. For the most accurate results, take each measurement twice and use the average. Use calipers with consistent pressure and measure on the right side of the body.
Try other methods
Don't have calipers? Try the U.S. Navy method or Covert Bailey method, both of which require only a tape measure. You can also enter a known value from a DEXA scan or scale using the manual entry option.
Frequently asked questions
What is the skinfold (Jackson-Pollock) method?
The Jackson-Pollock 3-site skinfold method estimates body fat percentage by measuring the thickness of subcutaneous fat at three specific body sites using a caliper. These readings are used to calculate body density, which is then converted to body fat percentage via the Siri equation. The method was developed and validated by Andrew Jackson and Michael Pollock in 1978 and is widely used in exercise science research and practice.
Why is skinfold considered the gold standard among field methods?
Skinfold testing directly measures subcutaneous fat at specific body sites rather than relying on proxy measurements like circumferences. When performed by a trained technician with accurate calipers, skinfold correlates closely with DEXA and hydrostatic weighing — the laboratory reference standards. It also accounts for sex and age differences in fat distribution, which circumference-based methods handle less precisely.
What is the difference between 3-site and 7-site skinfold?
The 3-site Jackson-Pollock method (used here) measures three body sites and is faster and practical for regular self-monitoring. The 7-site version adds four additional sites (subscapular, midaxillary, suprailiac, and triceps for men; chest, subscapular, midaxillary, and abdomen for women) for a more comprehensive picture. Research suggests the 3-site and 7-site protocols produce similar results when measurements are taken correctly.
How do I take accurate skinfold measurements?
Grasp the skin and underlying fat between your thumb and index finger approximately 1 cm above the measurement site, then apply the caliper jaws at the site itself. Read the caliper after about 2 seconds to let the jaws stabilize. Take each measurement twice and average the two readings. Measure on the right side of the body, avoid measuring immediately after exercise or bathing, and maintain consistent technique across sessions to ensure comparable results over time.
Can I do skinfold measurements on myself or do I need help?
The chest and abdomen sites are difficult to measure on yourself with consistent technique. The thigh site can be self-measured but is easier with a partner. For the most reproducible results — especially if you are tracking changes over time — having the same trained person take measurements each time is ideal. That said, self-measurement with care can provide a reasonable estimate for general monitoring.
How accurate is skinfold compared to DEXA or hydrostatic weighing?
In trained hands, the Jackson-Pollock 3-site method produces results that correlate closely with DEXA and hydrostatic weighing. Measurement error increases with poor technique, inconsistent site location, or calipers that are worn or poorly calibrated. The method tends to be less precise at very high or very low body fat levels, where fat distribution patterns differ from the populations used to develop the formula.
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