Specific Gravity Calculator
Calculate the specific gravity of a substance by comparing its density to that of water.
What specific gravity means
Specific gravity (also called relative density) is a dimensionless ratio comparing the density of a substance to the density of a reference substance, almost always water at 4°C (1000 kg/m³). It is calculated as SG = ρsubstance / ρreference.
How this calculator works
Enter the density of the substance you’re checking and the reference density (defaulting to fresh water at 1000 kg/m³). The calculator divides the substance density by the reference density to give a unitless specific gravity value, and notes whether the substance would float or sink in the reference fluid.
A specific gravity below 1 means the substance is less dense than the reference fluid and will float; above 1 means it is denser and will sink. This is a simplified comparison and does not account for surface tension or shape effects on floating. For general educational purposes.