Decimal Day

This article is part of a series on the
History of the English penny
The Anglo-Saxons (c. 600 – 1066) Early Normans and the Anarchy (1066–1154) Plantagenets (1154–1485) Tudors (1485–1603) Stuarts and Commonwealth (1603–1707) Hanoverians (1714–1901) 20th century (1901–1970) Decimal Day, 1971 Post-decimalisation (1971–present)
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Decimal Day (Irish: Lá Deachúil)^[1] in the United Kingdom and in Ireland was Monday 15 February 1971, the day on which each country decimalised its respective £sd currency of pounds, shillings, and pence.

Before this date, the British pound sterling (symbol "£") was subdivided into 20 shillings, each of 12 (old) pence, a total of 240 pence. With decimalisation, the pound kept its old value and name, but the shilling was abolished, and the penny was revalued, such that the pound was subdivided into 100 of what were originally called "new pence" ("NP"), and later just pence ("p") when confusion was no longer likely. Each new penny was worth 2.4 old pence (abbreviated "d.").

A coin of half a new penny, a halfpenny, was introduced to maintain the approximate granularity of the old penny, but was dropped in 1984 as inflation reduced its value. An old value of 7 pounds, 10 shillings, and sixpence, abbreviated £7-10-6 or £7:10s:6d. became £7.521/2p. Amounts with a number of old pence which was not 0 or 6 did not convert into a round number of new pence.

The Irish pound had the same £sd currency structure, and the same decimalisation was carried out.