Pinch chest, abdomen and thigh (men) or triceps, suprailiac and thigh (women) with a skinfold caliper, enter the numbers below, and get your body fat % using the Jackson-Pollock 3-site formula.
Reviewed by João Freitas · Formula: Jackson-Pollock 3-site (Siri)
Technique matters more than the caliper itself. Pinch skin plus the fat layer only - not the muscle underneath - hold the fold with two fingers, place the jaws about 1 cm below your fingers, and read the dial 1-2 seconds after releasing pressure. Take 2-3 readings per site and average them. Always measure on the right side of the body and at the same time of day.
Against a DEXA scan, a trained tester using the Jackson-Pollock 3-site method is typically within ±3-4 percentage points. Measuring yourself adds extra noise on top of that - inconsistent pinch location, pressure and hydration can all shift the number a point or two. That's fine: the absolute value matters less than measuring the same way every time so the trend over weeks is meaningful. If you can, have the same person measure you and always average 2-3 repeats per site.
Measured by a trained tester, it typically lands within about 3 to 4 percentage points of a DEXA scan. Self-measurement adds noise on top of that. Use it to track the trend over weeks, not as a single precise reading.
No. A basic spring-loaded skinfold caliper with consistent tension is enough for this formula to work. What matters far more than the device is pinching the same sites the same way every time.
Yes. Use our US Navy tape method instead, which only needs a measuring tape and your height, neck and waist (plus hip for women). See the body fat calculator page for that method.
The Jackson-Pollock equations were derived separately for men and women because fat is distributed differently by sex. Men use chest, abdomen and thigh; women use triceps, suprailiac and thigh. Using the wrong sites for your sex gives a meaningless number.
Need more precision? The 7-site Jackson-Pollock protocol adds four more skinfolds for a finer estimate.
No calipers on hand? Estimate body fat with just a measuring tape using the US Navy method.
The Jackson-Pollock 3-site method explained in depth, with a worked example and accuracy notes.
Disclaimer: educational purposes only. Not medical advice. If you have a medical condition, talk to a qualified professional.