Jackson-Pollock 4-Site Body Fat Calculator

The Jackson-Pollock 4-site body fat test estimates body fat percentage from four skinfold measurements and the subject's age. Its paper trail is worth stating plainly, because most sites get it wrong. The four-site equations for women come from Jackson, Pollock and Ward (1980), which derived three, four and seven-site versions. The men's four-site equation is in wide use, but we could not trace it to a primary publication. The 1978 Jackson-Pollock paper contains only three-site and seven-site equations, and the 1985 article usually credited for it is a practitioner review that recommends three sites, not four. It is part of a family of generalized equations Jackson and Pollock developed so that one formula could be used across adults of different ages and body compositions, instead of equations that only fit the group they were built on.

The defining feature of the JP 4-site method is that it uses the same four measurement locations for both males and females, namely tricep, suprailiac, abdomen, and thigh. This makes it simpler than the Jackson-Pollock 3-site skinfold calculator, which uses different sites for men and women. The fourth site doesn't clearly add accuracy, though. In the women's study, equations built on three, four and seven skinfolds performed about the same (Jackson, Pollock and Ward, 1980).

For a complete overview of all body fat measurement methods and how to use calipers, see our guide to measuring body fat.

If you don't have calipers, the US Navy body fat formula estimates body fat from simple tape-measure circumferences instead.

Who Is This Method For?

The JP 4-site method is a good choice if you want one set of sites for men and women without the time commitment of 7 measurements. That makes it practical for trainers or partners who measure several people.

Like the other JP formulas, this method was derived on general-population samples, so its accuracy in very lean or highly trained people is less well established. If that applies to you, consider the Yuhasz method (designed for athletes) or the Jackson-Pollock 7-site method for more comprehensive coverage.

Skinfold Measurement Locations (Males and Females)

All four measurement sites are the same for both males and females.

Site	Location	Fold Direction
Tricep	Halfway between the top of the shoulder and the elbow, on the back of the arm	Vertical
Suprailiac	Above the superior anterior iliac crest (the upper and forward protrusion of the hip bone)	Diagonal
Abdomen	One inch to the right of the belly button	Vertical
Thigh	Halfway between the kneecap (patella) and the inguinal crease (where the top of the thigh meets the hip)	Vertical

Jackson-Pollock 4-Site Formula for Males

Measure the following skinfolds in millimeters with body fat calipers. They are Tricep, Suprailiac, Abdomen, and Thigh.

Step	Formula
Body Fat %	(0.29288 x sum of skinfolds) - (0.0005 x sum of skinfolds²) + (0.15845 x age) - 5.76377

Unlike the JP 3-site and 7-site formulas, the JP 4-site equation outputs body fat percentage directly. There is no intermediate body density step and no need to apply the Siri equation.

Jackson-Pollock 4-Site Formula for Females

Measure the following skinfolds in millimeters with body fat calipers. They are Tricep, Suprailiac, Abdomen, and Thigh.

Step	Formula
Body Fat %	(0.29669 x sum of skinfolds) - (0.00043 x sum of skinfolds²) + (0.02963 x age) + 1.4072

Example Calculation

Here is a worked example for a 28-year-old female with the following skinfold measurements.

Site	Measurement
Tricep	16 mm
Suprailiac	14 mm
Abdomen	20 mm
Thigh	22 mm
Sum of Skinfolds	72 mm

Calculate Body Fat Percentage

Body Fat % = (0.29669 x 72) - (0.00043 x 72²) + (0.02963 x 28) + 1.4072

Body Fat % = 21.3617 - 2.2291 + 0.8296 + 1.4072

Body Fat % = 21.4%

If your result seems off, check that you used the formula for the right sex and that every skinfold is in millimeters.

Tips for Accurate Results

Measure at the same time of day. Morning measurements before eating produce the most consistent results. Hydration, meals, and exercise all affect skinfold thickness.

Take each measurement twice. If two readings at a site differ by more than 2 mm, take a third and average the two closest. Rotate through all four sites before remeasuring to give the skin time to return to its normal thickness.

Always measure from the right side. The Jackson-Pollock formulas were developed using right-side measurements. Switching sides introduces inconsistency.

Use the same calipers every time. Different caliper brands apply different jaw pressures, making results incomparable across brands.

Have a partner take measurements when possible. While three of the four sites can be self-measured, the tricep is easier and more accurate when someone else takes the reading. Consistency in who takes the measurements matters as much as consistency in technique.

How the JP 4-Site Compares to Other Methods

Method	Sites	Best For
JP 3-Site	3	Quick estimate, beginners
JP 4-Site (this article)	4	Same four sites for men and women
JP 7-Site	7	Most comprehensive JP method
Durnin-Womersley	4	Broad age range (16-72), age-specific equations
Yuhasz	6	Athletes and highly fit individuals
Parillo	9	Most detailed caliper method

Conclusion

The Jackson-Pollock 4-site method sits between the 3-site and 7-site methods in the JP family. Its main advantage is one set of four sites for men and women, which makes it convenient for trainers working with several clients or partners measuring each other.

If you want the simplest JP option, the 3-site method needs one fewer measurement. If you want more sites, the 7-site method measures seven. And if you want a different four-site approach with age-specific equations, the Durnin-Womersley method is a strong alternative.