Petroleum & Drilling
Basic

API Gravity

Standard measure of how light or heavy a crude oil is relative to water.

Formula

API=141.5SG−131.5API = \frac{141.5}{SG} - 131.5

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Variables

APIAPI gravity (°)
SGSpecific gravity at 60°F

Example

SG=0.85: API = 166.5-131.5 = 35°

Did You Know?

Crude above 31° API is 'light'; below 22° is 'heavy' and harder (pricier) to refine.

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