A butt approximately equated to 108 imperial gallons (130 US gallons; 491 litres; 5 hectolitres) for ale or 126 imperial gallons (151 US gallons; 573 litres; 6 hectolitres) for wine (also known as a pipe), although the Oxford English Dictionary notes that "these standards were not always precisely adhered to".
- "Butt, n.2". Oxford English Dictionary.
- Ciphering (1833). Ciphering made easy, or, An attempt to render simple and interesting the first four rules of arithmetic. p. 84. ISBN 978-0559229732. Retrieved 2016-03-18.