Density of an oil sample, at 15.5^oC (60^o F), is measured with Anton Paar DMA38 pychnometer. Using a glass syringe, the cell of the instrument is filled with the sample avoiding to have air bubbles. The instrument is adjusted using air and degased distilled water. The instrument also provides specific gravity (SG).

API gravity is calculated with the equation:

API (^o) =141.5/ SG (60^oF) – 131.5