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Health · Body Measurements & Composition

Three-Site Skinfold Body Fat Calculator

For trained measurement use, estimate body density and body-fat percentage from the sex-specific Jackson-Pollock-Ward three-site equations.

Health · Body Measurements & Composition

Enter your measurements

Professional entered-value arithmetic · private in-browser calculation
Professional intended use

This route reproduces arithmetic from verified source measurements. It does not validate the measurements, diagnose, select treatment, or replace the applicable clinical protocol.

Health values stay in this browser tab. They are not added to the URL, analytics, storage, or a cloud record.

Health result

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Enter valid values to see the result.

Your entries are calculated in this browser and are not submitted to 365CALCS.COM.

Quick guide

How to use this calculator

  1. Use the labels and unit notes to enter the requested measurement, date, time, or observation exactly as recorded.
  2. Check the visible method, population, and unit basis before using the result; switch modes rather than converting values mentally.
  3. Read the calculation audit and limitations together. The result supports measurement or tracking and does not replace diagnosis, treatment, or urgent medical assessment.

Calculation method

How the three-site skinfold body fat calculator works

The source male equation uses chest + abdomen + thigh; the source female equation uses triceps + suprailiac + thigh. Each estimates density from skinfold sum and age, then Siri converts density to body-fat percentage.

This is a method-specific anthropometric estimate. The displayed body density is the regression output, not a hydrostatic or air-displacement measurement.

Worked example

Three-Site Skinfold Body Fat example

For the male equation at age 30 with 10, 20, and 15 mm skinfolds, the three-site sum is 45 mm and the Siri estimate is about 13.6%.

The source male equation uses chest + abdomen + thigh; the source female equation uses triceps + suprailiac + thigh. Each estimates density from skinfold sum and age, then Siri converts density to body-fat percentage.

Supported inputs

Precision and limits

Supported purpose

Requires trained caliper technique and the exact named landmarks. The release is restricted to source ages and a three-site sum no greater than 120 mm; it does not provide normative body-fat categories.

Measurement quality

The output is only as reliable as the entered measurement, device, timing, units, and applicable reference population. Recheck unexpected values against the original record.

Clinical boundary

This calculator does not diagnose a condition, choose treatment, change medication, or determine that an urgent symptom is safe to monitor at home. Contact an appropriate health professional or local emergency service when the situation may be urgent.

Privacy

Entered health values and results stay in this browser tab. They are not placed in URLs, analytics, logs, local storage, session replay, or a cloud record by this calculator.

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