predecimal

Predecimal refers to monetary systems used before the adoption of decimal currency. The most familiar example is the United Kingdom’s system, which operated on pounds, shillings, and pence until Decimal Day in 1971. The term is also used more broadly to describe any currency that remained non-decimalised before its decimal reform.

In the predecimal British system, the basic units were the pound (£), the shilling (s or /-) and the penny (d). There were 12 pence in a penny and 20 shillings in a pound, giving 240 pence to a pound. Denominations included coins and notes of various values, and the notation L, s, and d (from Latin libra, solidus, denarius) was commonly used in accounting and prices. A guinea, worth 21 shillings, persisted for some transactions in earlier centuries. The transition to decimal currency simplified arithmetic by replacing the mixed base system with a uniform decimal base, while leaving many familiar names and denominations in historical use.

Decimalisation in Britain began after years of planning, culminating in Decimal Day on 15 February 1971. The new currency introduced the pound as 100 pence and a new set of coins and banknotes, with price markings, cash registers, and accounting systems converted accordingly. The changeover was accompanied by transitional measures to ease adoption, including dual pricing in some cases.

Outside the United Kingdom, several Commonwealth countries also moved to decimal currencies in the mid-20th century, notably Australia in 1966 and New Zealand in 1967. The term predecimal thus broadly denotes monetary systems prior to decimal reform and is used in historical and comparative discussions of currency.