API gravity

American Petroleum Institute measure of specific gravity of crude oil or condensate in degrees. An arbitrary scale expressing the gravity or density of liquid petroleum products. The measuring scale is calibrated in terms of degrees API; it is calculated as follows: Degrees API = (141.5 / sp.gr.60 deg.F/60 deg.F) - 131.5

The gravity (weight per unit volume) of crude oil or other related liquids as measured by a system recommended by the American Petroleum Institute. API Gravity is expressed in degrees, a specific gravity of 1.00 being equivalent to 10 API. API gravity is related to specific gravity (SG) by the following formula: API Gravity = (141.5 /Specific Gravity) - 131.5.