The imperial gallon is a standard unit of measurement for liquids used in some countries, including the United Kingdom and Canada. This unit of measurement is also known as the UK gallon or the Royal gallon. It is equivalent to 4.546 liters or 1.2 US gallons. Other synonyms for the imperial gallon include the Winchester gallon, which was used in England in the past, and the Queen Anne gallon, which was introduced during Queen Anne's reign in the early 18th century. Regardless of the name, it remains an important unit of measure for various industries, including breweries and fuel suppliers.