Specific Gravity (density)

The Specific Gravity for Solids and Liquids equation (SG = ρ / ρ_w) computes the Specific Gravity (SG) of a substance based on the ratio of mass density to density of water under standard conditions (4ºC).  
INSTRUCTIONS: Choose units and enter the following:

• (ρ) The mean density of the object or liquid.
• (ρ_w) The mean density of water  (default is 1,000 kg/m³)

Specific Gravity (SG): The calculator returns the Specific Gravity ratio, a unitless value.   

Related Calculators:

• Compute the mean density of an object or liquid based on the specific gravity,CLICK HERE.

The Math / Science

Specific gravity is a ratio of densities, where the density of an item is compared to  (divided by) the density of a common substance.  We often see specific gravity as the ratio of the density of a material compared to the density of water.

The formula for specific gravity is: 

        SG = ρ / ρ_w

where:

• SG is the specific gravity
• ρ is the density of the material
• ρ_w is the density of the comparative substance (e.g. water at 1,000 kg/m³)

Mean Density

The mean density of water in this equation has a default of 1000 kg/m³.  However, the user can enter other values for the denominator density.  For gases, the specific gravity is nearly always based on the mean density of air at room temperature (21ºC).