the chemical engineering processes and other facilities used in petroleum refineries (also referred to as oil refineries) to transform crude oil into useful products such as liquefied petroleum gas, gasoline or petrol, kerosene, jet fuel, diesel oil and fuel oils.

Petroleum refining in the United States in 2024 had a capacity of 18.4 million barrels per day.

Petroleum refining in the United Kingdom produced around 51.45 million tonnes of petroleum products in 2023, down 16% from 2015 and 32% from 2011.