How pounds, shillings and pence worked

For over a thousand years Britain counted money in pounds, shillings and pence. Here's how the system worked, why it lasted so long, and how to read and add up amounts you find in old documents.

The basic rules

• 12 pence (d) = 1 shilling (s)
• 20 shillings = 1 pound (£)
• So 240 pence = £1
• A penny could be split into 2 halfpennies or 4 farthings.

If you remember nothing else, remember 12 and 20. Every sum in old money comes back to them.

Why £, s and d?

The abbreviations are Latin: librae (pounds), solidi (shillings) and denarii (pence). The idea goes back to the early Middle Ages, when a pound weight of silver was struck into 240 silver pennies. For centuries the penny was the only coin most people handled; the shilling and the pound began as units for counting, long before they became coins.

How amounts were written

Pronunciation was its own art: “tuppence”, “thruppence”, “fippence” for 5d, and “ha'penny” (HAY-pnee) for a halfpenny.

Doing sums in old money

Add the pence first and carry every 12 pence as a shilling. Then add the shillings and carry every 20 as a pound. Then add the pounds. For example:

£2 15s 9d + £1 7s 6d. Pence: 9 + 6 = 15d = 1s 3d (write 3d, carry 1s). Shillings: 15 + 7 + 1 = 23s = £1 3s (write 3s, carry £1). Pounds: 2 + 1 + 1 = £4. Answer: £4 3s 3d.

The £sd calculator does all of this for you, including halfpennies and farthings.

Decimal Day: 15 February 1971

On Decimal Day Britain kept the pound but divided it into 100 new pence. Some old amounts converted neatly: a shilling became 5p, a florin 10p and sixpence 2½p. Others did not. An old penny was worth 5/12 of a new penny, about 0.42p. Use the old money converter to convert any amount exactly.

Why did it last so long?

Twelve and twenty divide in many useful ways. A shilling splits evenly into halves, thirds, quarters and sixths, and a pound into thirds as 6s 8d each. For shopkeepers selling by the dozen, and for people doing sums in their heads, that was genuinely convenient. Its weakness was written arithmetic, which grew more painful as banking, trade and later computers took over.

Quick conversions

Want to know what a sum would buy today? Try the worth today calculator.