Specific gravity

Also known as: SPG

Specific gravity is an index used to measure the density of a liquid. Specific gravity is calculated as the ratio of the density of a liquid to the density of water. So any liquid with a density greater than water has a specific gravity greater than 1. Liquids with a density lower than water, which includes most crude oil grades and petroleum products, will have a specific gravity between 0.0 and 1.0.

In the oil industry, specific gravity is a common quality specification for finished products. However, for crude oil grades, the API gravity index is more commonly used.

Calculation of specific gravity from API gravity:

Specific gravity = 141.5/(API gravity + 131.5)

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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