Decimalization refers to any process of converting from traditional units, usually of money, to a decimal system.

This process has been undergone by all countries except Mauritania and Madagascar, but in practice these currencies are of such low value that the subsidiary denominations have fallen out of use - the Euro is currently worth approximately 250 Mauritanian Ouguiyas (MRO), each of which theoretically contains 5 khoums, while the Euro is worth approximately 2,500 Madagascan Ariaries (MGA) of 5 iriambilanja.

France decimalised first, abandoning the Livre tournois at the time of the Revolution, and imposed decimalisation on a number of countries that it invaded at that time. The United States introduced a decimal currency after achieving independence from Britain. However, many Commonwealth countries retained traditional money systems (pounds, shillings and pence) after achieving effective independence as Dominions, and only decimalised in the second half of the 20th century.

South Africa decimalised in 1961, introducing the rand as the new unit of currency. When Australia decimalised in 1966, the new Australian dollar was fixed at ten shillings (i.e. half an Australian pound). A similar strategy was followed in New Zealand in 1967, with the introduction of the New Zealand dollar.

The United Kingdom and the Republic of Ireland decimalised the Pound Sterling and the Irish pound on Decimal Day, 15 February 1971.

Many other former British colonies, such as Singapore, Malaya, Sri Lanka, Mauritius, and the Seychelles used decimal currencies, even while under British rule.

India changed from the Rupee, Anna, Pie system to decimal currency in 1957. Pakistan followed in 1961. Sri Lanka (formerly Ceylon) has used a decimal currency since 1869.

In France, decimalisation of the coinage was accompanied by metrication of other measures. However, in general the two have not gone hand in hand: the U.S. has never metricated, Canada has only recently done so despite having had a decimal coinage since 1859, and the U.K. has only metricated to a limited extent. The U.S. stock exchanges, however, did convert from fractions of dollars to decimals from 2000 to 2001.

Decimalisation in the United Kingdom

The switch from pounds shillings and pence to decimal currency started with the introduction of the 5p and 10p coins in 1968. The new coins were the same size and value as the old 1 shilling and 2 shilling coins respectively, and served to introduce the new decimal currency smoothly. The new 50p coin was introduced in 1969.

Decimalisation was completed on 15 February 1971 with the introduction of ½p, 1p, and 2p coins. The 20p coin came out in 1982, and the £1 coin in 1983. The old sixpence continued to circulate, valued at 2½p, but ceased to be legal tender in 1980.

The changeover period was originally scheduled to last a year, but the old currency stopped being used in about half that time. The old shilling and two shilling coins remained in circulation long after decimalisation, much to the confusion of visitors. They were finally withdrawn after new, smaller 5p and 10p coins were issued in 1990 and 1992.

See also

• British coinage