Skinfold Body Fat Calculator
Calliper measurements through the Jackson-Pollock equations.
Calliper readings (mm)
Estimated body fat
Callipers are accurate and unforgiving
The Jackson-Pollock 3-site method measures subcutaneous fat at three points, converts the sum tobody density via a regression equation, then converts density to a percentage using the Siri equation. Age is in the formula because fat distribution shifts inward over time, so the same sum of folds means more total fat at 50 than at 20.
The sites differ by sex and are not interchangeable. Men use chest, abdomen and thigh; women use triceps, suprailiac and thigh. Using the wrong set invalidates the result entirely, because the regression was fitted to those specific locations. Each site has a defined position, orientation and pinch technique — an abdominal fold is vertical, roughly 2 cm right of the navel, and a chest fold is diagonal.
In trained hands callipers are accurate to within about 3% of hydrostatic weighing, which is better than any circumference method. In untrained hands they are considerably worse, because consistency of site, pinch depth and timing all matter. Take each reading three times and use the median, measure on the right side of the body, and always have the same person measure — inter-tester variation is the single largest source of error.
Medical disclaimer. This calculator is for general information and education only. It is not medical advice, not a diagnosis, and not a substitute for professional care. Skinfold equations were derived in specific populations and are less reliable at very high body fat, where folds exceed calliper range.Speak to a doctor or another qualified clinician about any health decision.Last reviewed .
Frequently asked questions
Which sites does the 3-site method use?
Men measure chest, abdomen and thigh. Women measure triceps, suprailiac and thigh. The sites are not interchangeable between sexes — the regression equations were fitted to those specific locations.
How accurate are skinfold callipers?
Within roughly 3 percentage points of hydrostatic weighing when performed by an experienced tester, which is better than any tape-based method. Accuracy falls off sharply with inconsistent technique, which is the dominant source of error.
Why does the formula need my age?
Because fat distribution shifts from subcutaneous toward visceral stores with age. The same sum of skinfolds therefore corresponds to a higher total body fat in an older person, and the equation corrects for that.
Should I measure left or right side?
The right side, which is the convention the Jackson-Pollock equations were developed with. What matters most is consistency — pick a side and always use it.
What is the Siri equation?
The conversion from body density to fat percentage: 495 divided by density, minus 450. It assumes standard densities for fat and lean tissue, which is why it is slightly less accurate for populations whose bone density differs from the reference.