How to Calculate Body Fat with the Jackson-Pollock 4 Body Fat Formula

The Jackson-Pollock 4-site body fat test, published in 1985 by Dr. Andrew Jackson and M. L. Pollock as a simplified alternative to their earlier generalized equations, estimates body fat percentage from four skinfold measurements and the subject's age. It is part of a family of related equations the two researchers created to make body fat estimation accessible without expensive equipment.

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The defining feature of the JP 4-site method is that it uses the same four measurement locations for both males and females: tricep, suprailiac, abdomen, and thigh. This simplifies the process compared to the JP 3-site method, which requires different sites depending on gender. The additional fourth site also provides a broader sample of fat distribution, which generally improves accuracy.

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

Who Is This Method For?

The JP 4-site method is a good choice for anyone who wants a step up in accuracy from the 3-site method without the time commitment of 7 measurements. Because the sites are the same for both genders, it is also practical for trainers or partners who measure multiple people.

Like the other JP formulas, this method is designed for the general population and may underestimate body fat in very lean individuals, including competitive bodybuilders and performance athletes. 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: 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: 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%

Note: 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 calculation and no need to apply the Siri equation. If your result seems off, double-check that you are using the correct formula for the subject's gender and that all skinfold measurements are 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 sites for both genders, good accuracy-to-effort ratio
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

Supporting Your Body Composition Goals

Consistent body fat tracking gives you the data to make informed decisions about your nutrition and training. Pairing that data with targeted nutritional support can help you work toward your goals more effectively.

FitFast combines berberine, a naturally occurring plant alkaloid, with InSea2, a blend of polyphenols derived from sustainably harvested brown seaweed. This combination is formulated to support healthy blood glucose levels and a healthy glycemic response to food.

Conclusion

The Jackson-Pollock 4-site method occupies a practical middle ground in the JP family: more thorough than the 3-site method, less time-consuming than the 7-site. The fact that it uses the same four sites for both males and females makes it especially convenient for trainers working with multiple clients or partners measuring each other.

If you want the simplest possible JP option, the 3-site method requires one fewer measurement. If you want maximum accuracy within the JP framework, the 7-site method provides the most comprehensive coverage. And if you want a different four-site approach with age-specific equations, the Durnin-Womersley method is a strong alternative.