API gravity

API gravity is a commonly used index of the density of a crude oil or refined products. API stands for the American Petroleum Institute, which is the industry organization that created this measure.

Calculation of API gravity

API is calculated from a hydrocarbon's specific gravity using this formula:

API = (141.5/Specific Gravity) - 131.5

API gravity of crude oil grades

A crude oil will typically have an API between 15 and 45 degrees. Higher API indicates a lighter (lower density) crude. Lower API indicates a heavier (more dense) crude. Generally, lighter (high API) crudes are more valuable because they yield more high-value light products when run through a refinery.

Light crude is typically in the 35-45 API range, which includes most of the highest valued crudes such as Brent and WTI. Crudes lighter than 45 are typically considered extra-light crude or condensates and are valued lower than light crude because they contain a lot of light ends such as propane and butane. A medium crude is in the 25-35 API range, and a heavy crude is in the 15-25 API range. Anything below 15 API would be considered an extra-heavy crude.

The Refinery Reference Desk includes content derived from our industry experts as well as from public data sources such as company websites. Nothing herein is intended to serve as investment advice. This material is based on information that we believe to be reliable and adequately comprehensive, but we do not represent that such information is in all respects accurate or complete. McKinsey Energy Insights does not accept any liability for any losses resulting from use of the content.

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