Skinfold Body Fat Calculator
Jackson-Pollock 3-site caliper method.
Calculate body fat percentage from three skinfold caliper measurements using the Jackson-Pollock equations, with site guidance for men and women.
Chest for men, triceps for women.
Abdomen for men, suprailiac for women.
Site location is the biggest source of error. When tracking change over time, have the same person take every measurement the same way.
Body fat (Jackson-Pollock)
13.6%
Accuracy is roughly ±3–5 percentage points against DEXA in trained hands, and worse without practice.
How the Skinfold Body Fat Calculator works
Skinfold calipers measure the fat directly under the skin at set sites, and regression equations convert those thicknesses into a whole-body estimate. Done consistently by the same person, the method tracks change well, the technique matters far more than the calipers.
Also known as: caliper body fat calculator · Jackson Pollock skinfold · 7 site skinfold calculator · body fat calculator caliper · body fat caliper calculator · body fat calculator using calipers · body density calculator
How skinfold measurement works
Calipers measure the thickness of a fold of skin and the subcutaneous fat beneath it at defined sites. Prediction equations convert those thicknesses into an estimated body density, and a further equation converts density into a body fat percentage.
The most widely used equations are Jackson and Pollock, published in 1978 for men and 1980 for women, using either three or seven sites. Durnin and Womersley, from 1974, uses four sites and is common in the UK.
Converting density to fat percentage is usually done with the Siri equation, which assumes fixed densities for fat and lean tissue. That assumption is reasonable for most adults and less so for children, older adults and some ethnic groups, which is a source of error separate from the measurement itself.
The sites, and why they must be exact
The three-site Jackson and Pollock protocol for men uses chest, abdomen and thigh; for women, triceps, suprailiac and thigh. The seven-site version adds subscapular, midaxillary and either chest or triceps.
Each site has a precise anatomical definition, and measuring a centimetre away from it produces a different thickness. The abdominal site in particular is defined as a vertical fold two centimetres to the right of the navel, and a horizontal fold at the same place gives a different reading.
Which means the protocol has to be followed exactly and the same way each time. Most of the variation between practitioners comes from site location rather than from the calipers.
Technique
Pinch the fold firmly between thumb and forefinger, a centimetre above the site, lifting the skin and fat away from the underlying muscle. Apply the calipers perpendicular to the fold and read after one to two seconds, before the tissue compresses further.
Take each site three times and use the median rather than the mean, which reduces the effect of a single bad reading.
Measure on the same side of the body every time. Jackson and Pollock specify the right side; some other protocols use the left. Mixing sides between sessions introduces a difference that has nothing to do with body composition.
Accuracy, honestly stated
In experienced hands with a good caliper and a correctly applied protocol, skinfold estimates typically land within three to four percentage points of a DEXA measurement.
In inexperienced hands the error is considerably larger, and self-measurement is particularly unreliable for the sites on the back and the thigh, which are difficult to pinch correctly on oneself.
The method also assumes that subcutaneous fat is a consistent proportion of total fat, which varies between individuals and with age. Someone carrying a high proportion of visceral fat will be underestimated by any skinfold method, and that is precisely the fat that matters most.
Using it for tracking
Where skinfold measurement genuinely excels is in tracking change, provided the same person measures the same sites with the same calipers each time.
Under those conditions the systematic errors cancel out and the change in the sum of the folds is a reliable indicator of the direction of change, even if the absolute percentage is imprecise.
Which suggests recording the raw millimetre readings at each site rather than only the converted percentage. The raw numbers are the actual measurement; the percentage is an estimate built on top of them with additional assumptions, and it is the assumptions rather than the measurement that most of the error comes from.
Where to go next
The Skinfold Body Fat question rarely arrives on its own. These are the ones that usually come with it:
- Body Fat Calculator — Body fat percentage from tape measurements.
- Lean Body Mass Calculator — Everything you weigh that is not fat.
- FFMI Calculator — Fat-free mass index, muscularity adjusted for height.
- BMI Calculator — Body mass index with category and healthy weight range.
Not medical advice. This calculator gives a general estimate, not medical advice. It cannot account for your individual health, medical history, or medication. Talk to a qualified healthcare professional before acting on any result.
Frequently asked questions
Which sites does the 3-site method use?
For men: chest, abdomen and thigh. For women: triceps, suprailiac and thigh. The sites differ because the underlying equations were derived separately for each, so using the wrong set gives a wrong answer.
How do I take a skinfold measurement properly?
Pinch the skin and fat firmly, pulling it away from the muscle, and place the calipers about a centimetre from your fingers at the midpoint of the fold. Read after roughly two seconds. Take three readings at each site and use the median. Always measure the right side of the body.
How accurate are skinfold calipers?
About ±3–5 percentage points against DEXA in trained hands, and considerably worse in untrained ones. The single biggest source of error is inconsistent site location, which is why the same tester should take every measurement when tracking change.
Skinfolds or the tape measure method?
Skinfolds are more accurate when done well but need equipment and practice; the US Navy tape method needs only a tape and is more repeatable for most people. For tracking your own trend, the more repeatable method usually wins.
Related calculators
Body Fat Calculator
Body fat percentage from tape measurements.
OpenLean Body Mass Calculator
Everything you weigh that is not fat.
OpenFFMI Calculator
Fat-free mass index, muscularity adjusted for height.
OpenBMI Calculator
Body mass index with category and healthy weight range.
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