Specific Gravity

Written by Jerry Ratzlaff. Posted in Dimensionless Numbers

Specific gravity is the density or ratio of any substance to another substance.  It sometimes may be called just gravity or relative density.  When calculating the specific gravity of a liquid or solid, water is normally the comparison (water has a specific gravity of 1). 

Even though two objects are the same size, their density may be different. This is expressed in how much more weight the object is in comparison to the same amount of water.  Likewise a gas is compared to air.


\(SG = \frac { \rho_s } { \rho_w  } \)


\(SG\) = specific gravity

\(\rho_s\) (Greek symbol rho) = sample density

\(\rho_w \) (Greek symbol rho) = water density

Solve for:

\(\rho_s = SG \rho_w  \)

\(\rho_w = \frac { \rho_s } { SG  } \)

conversion table

  • This is a Density Conversion
Specific Gravity Conversion Table
MultiplyByTo Get
  436995.7259 grain per cubic foot
  252.8910451 grain per cubic inch
  1 gram per cubic centimeter
  1e+15 gram per cubic kilometer
  1000000 gram per cubic meter
  0.001 gram per cubic millimeter
  1000000 gram per kiloliter
  1000 gram per liter
  1 gram per milliliter
  0.001 kilogram per cubic centimeter
  1e+12 kilogram per cubic kilometer
  1000 kilogram per cubic meter
  1e-15 kilogram per cubic micrometer
  0.000001 kilogram per cubic millimeter
  998.8473734 ounce per cubic foot
  0.578036674 ounce per cubic inch
  62.42796084 pound per cubic foot
  0.036127292 pound per cubic inch
  1 standard conditions
  1 specific gravity, water