API Gravity

API (American Petroleum Institute) gravity is a dimensionless measure of the density of a petroleum liquid (e.g. oil) compared to water.

For an API gravity greater than 10, a petroleum liquid will float on water. Conversely, an API gravity less than 10, will cause petroleum liquid to sink in water.

As such, an oil with a low specific gravity will have a high API gravity.

Table of API values

API Specific Gravity Density (std condns)
lb/US gal kg/m³
4 1.044 8.699 1042.4
5 1.037 8.636 1034.8
10 1.000 8.330 998.2
15 0.966 8.046 964.1
20 0.934 7.781 932.3
25 0.904 7.532 902.5
30 0.876 7.299 874.6
35 0.850 7.080 848.3
40 0.825 6.873 823.6
45 0.802 6.678 800.3
50 0.780 6.494 778.2

API / S.G. Converter

API -> S.G. Converter:

Formula: API = (141.5 / SG) – 131.5
S.G.:
 
Result: units

S.G. -> API Converter:

Formula: SG = 141.5 / (API + 131.5)
API Gravity:
 
Result: units