CALCULATE WITH CONFIDENCE

Health · Body Measurements & Composition

Body Density to Body Fat Calculator

Convert an independently measured body density to estimated body-fat percentage with an explicitly selected Siri or Brozek model.

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

—

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 body density to body fat calculator works

Siri body fat % = 495 / density - 450; Brozek body fat % = 457 / density - 414.2, with density in g/cm³.

The models use different two-component assumptions, so their estimates are not interchangeable and can differ for the same density.

Worked example

Body Density to Body Fat example

At a measured density of 1.05 g/cm³, Siri estimates 21.4% and Brozek estimates 21.0% body fat.

Siri body fat % = 495 / density - 450; Brozek body fat % = 457 / density - 414.2, with density in g/cm³.

Supported inputs

Precision and limits

Supported purpose

Enter density measured by an appropriate validated method and use the conversion required by that protocol. The calculator does not determine which model applies or classify the result.

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.

Continue calculating

Related calculators