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Body Fat (Skinfold 3 Site) Calculator

Work out body fat (skinfold 3 site) instantly with clear inputs, formula shown and shareable results.

About Body Fat (Skinfold 3 Site) Calculator

The Jackson-Pollock three-site equation predicts body density from the sum of chest, abdomen and thigh folds for men (or triceps, suprailiac and thigh for women) plus age, then converts density to fat percentage with the Siri equation. A 37 mm sum at age 30 gives a density near 1.0709 and about 12.3% fat.

Formulas

Jackson-Pollock 3-site density

D = 1.10938 - 0.0008267 x sum + 0.0000016 x sum^2 - 0.0002574 x age

Siri conversion

%fat = 495 / D - 450

Worked example

With the default values below, Body Fat (Skinfold 3 Site) Calculator returns Estimated Body Fat of 11.21%. Change any input above and every figure here is recalculated in your browser.

Inputs used

First site skinfoldminimum 1 mm
12 mm
Second site skinfoldminimum 1 mm
15 mm
Third site skinfoldminimum 1 mm
10 mm
Ageaccepts 10–90 years
30 years

Results

Estimated Body Fat
11.21%
Sum Of Skinfolds
37.0 mm
Estimated Body Density
1.0733 g/cm3
Category
Fit

Step by step

  1. 1Values used
  2. 2Jackson-Pollock 3-site density
  3. 3Siri conversion
  4. 4Estimated Body Fat= 11.21
  5. 5Sum Of Skinfolds= 37.0 mm
  6. 6Estimated Body Density= 1.0733 g/cm3
  7. 7Category= Fit

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • These figures are population-average estimates, not a medical assessment or diagnosis. Body composition equations carry errors of several percentage points, and healthy ranges vary with age, ethnicity, muscularity and medical history. Discuss weight or body composition goals with a qualified clinician or dietitian.
  • This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

These figures are population-average estimates, not a medical assessment or diagnosis. Body composition equations carry errors of several percentage points, and healthy ranges vary with age, ethnicity, muscularity and medical history. Discuss weight or body composition goals with a qualified clinician or dietitian.

Frequently Asked Questions

Why does age appear in the equation?

Because a given amount of subcutaneous fat corresponds to more internal fat as people age, so the same folds imply higher total fat.

How consistent must the pinch be?

Very. Take three readings at each site, use the median, and always pinch the same anatomical landmark - technique dominates the error.

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