Skinfold Body Fat Calculator (Jackson-Pollock 3-Site)
Turns three caliper readings into a body fat estimate.
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
The formula
men: density = 1.10938 − 0.0008267S + 0.0000016S² − 0.0002574a women: density = 1.0994921 − 0.0009929S + 0.0000023S² − 0.0001392a body fat % = 495 ÷ density − 450
S is the sum of the three skinfolds in mm and a is age in years. Men use chest, abdomen and thigh. Women use triceps, suprailiac and thigh.
What to watch out for
The men’s equation is from Jackson and Pollock (1978), built on men aged 18 to 61. The women’s is from Jackson, Pollock and Ward (1980), built on women aged 18 to 55. Siri’s equation converts density to body fat.
Take the folds on the right side of the body, on relaxed skin. Measure each site two or three times and use the average. Categories are from the American Council on Exercise. It is not valid in pregnancy.
Frequently Asked Questions
What would a 30-year-old man with a 60 mm sum read?
About 17.9%. A 30-year-old woman with the same sum would read about 24.1%.
Why does age change the result?
Fat under the skin makes up less of total body fat as people age, so the same readings give a higher estimate. A 60 mm sum for a man reads 20.2% at 50.
Skinfolds or tape measure?
Done by a practised tester, skinfolds can be the better estimate, but in unpractised hands they can be less reliable than a tape.