The American Petroleum Institute established the API gravity measure as a measure of the density of petroleum products relative to water. The greater the API gravity, the lighter the hydrocarbon liquid. The scale of API gravity is adjusted so that most petroleum liquids fall between 10 and 70 degrees API gravity. The formula can be reversed to find the density of the petroleum liquid.
The formula for API gravity is as follows;
API = (141.5/SG) -131.5 where SG is the specific gravity of the petroleum liquid being measured.
For example, API=22.3, calculate Specific Gravity.
22.3 = (141.5/SG)-131.5, then SG=0.92