Use this body-composition measurement as a screening or estimation aid when the required measurements were collected with the method and units stated by the tool.

Measured body density (g/cm3)

Required number input.

Conversion equation

Optional string input.

Convert a measured whole-body density to an estimated body-fat percentage with the Siri or Brozek equation. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Estimated body fat (%)

The resulting estimated body fat returned as a number.

• Population equations and screening indices do not directly diagnose health or measure every body compartment. Hydration, age, sex, ethnicity, athletic build, measurement technique, and the population used to derive an equation can affect interpretation.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Interpret the result with other measurements, trends, medical history, and professional guidance. Use a validated reference method when individual body composition must be measured more directly.

• Jackson–Pollock 3-Site Body Fat Calculator

  Estimate body density and body-fat percentage from the sex-specific Jackson–Pollock three-site skinfold equation and Siri conversion.

• Air-Displacement Body Composition Calculator

  Calculate density and estimated body composition from body mass and a corrected body volume measured by air-displacement equipment.

• Gonadosomatic Index

  Express gonad mass as a percentage of whole-body mass.