Pound avoirdupois
This is the measure of weight traditionally used in Britain for normal purposes until it was abolished - for pre-packed goods in 1995, and for loose produce in 2000. (There were other, different, measures used in specialised trades - troy measure was used with precious metals, apothecary's in pharmacy, etc.) The name imperial means that it was a unit established by an Act of (the UK) Parliament, in the days of the British Empire, and was an early attempt at a national standard, to replace various different local measures. Avoirdupois originally meant 'goods of weight', and is a better word, in the twenty-first century, for the system of weights which is shared, mostly, by the USA and the UK, as well as many other countries that share their traditions.
In the avoirdupois system, a pound (abbreviation: lb.) contains 16 ounces (oz.). Sweets and similar small items were commonly sold by the quarter (i.e. 'quarter of a pound' = 4 ounces). There are 14 pounds in a stone (st.), 8 stone (=112 pounds) in a hundredweight (cwt.) and 20 hundredweight (=2240 lb.) in a ton (note the spelling).
Confusingly, there was also quarter (i.e. of a hundredweight) that contained 2 stones. It was also possible to confuse different forms of ton as used to measure shipping capacity, wheat, timber etc.
The rough equivalents (for casual, not scientific or commercial use) of these in the metric system are:
| Avoirdupois (British) | Abbreviation | Metric |
|---|---|---|
| 1 ounce | oz | 28 grams |
| 1 quarter | qtr | 100 grams (hectogram) |
| 1 pound | lb | 454 grams (almost half a kilo) |
| 1 hundredweight | cwt | 50 kilograms |
| 1 ton | t | 1 tonne (approximately) |
Although the metric tonne and the British ton are approximately the same, more accurately, the British ton of 2240 lb. is 1016 kilos. The metric tonne (1000 kilos) is 2204.6 lb.
In the United States, there are some variations in the avoirdupois system from that in Britain. A hundredweight in the US is - more logically - 100 pounds, giving a ton of 20 cwt as 2000 lb. This is called the short ton, to distinguish it from the ton of 2240 lb., which is also recognised in the USA - as the long ton. The stone is not commonly recognised as a unit of weight in the United States. People talking about their body weights commonly use 'stones' in the UK ("I'm 8 1/2 stone" - note that the plural is expressed by the singular form, '8 1/2 stone', not stones). If more detail is needed, we use pounds: "He weighed in at 15 stone 6 lb.", "she was only 5 stone 3 when she went in to hospital"). In the USA, bodyweight is always expressed simply in pounds: "She weighs 113 pounds"; "How heavy are you?"/"Oh, 205."
