A pennyweight (dwt) is a unit of

mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different ele ...

equal to 24

grains A grain is a small, hard, dry fruit (caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and legumes ...

, of a

troy ounce Troy weight is a system of units of mass that originated in 15th-century England, and is primarily used in the precious metals industry. The troy weight units are the grain, the pennyweight (24 grains), the troy ounce (20 pennyweights), and th ...

, of a

troy Troy ( el, Τροία and Latin: Troia, Hittite: 𒋫𒊒𒄿𒊭 ''Truwiša'') or Ilion ( el, Ίλιον and Latin: Ilium, Hittite: 𒃾𒇻𒊭 ''Wiluša'') was an ancient city located at Hisarlik in present-day Turkey, south-west of Ç ...

pound, approximately 0.054857

avoirdupois ounce The ounce () is any of several different units of mass, weight or volume and is derived almost unchanged from the , an Ancient Roman unit of measurement. The avoirdupois ounce (exactly ) is avoirdupois pound; this is the United States customa ...

and exactly 1.55517384

gram The gram (originally gramme; SI unit symbol g) is a unit of mass in the International System of Units (SI) equal to one one thousandth of a kilogram. Originally defined as of 1795 as "the absolute weight of a volume of pure water equal to th ...

s. It is abbreviated dwt, ''d'' standing for ''

denarius The denarius (, dēnāriī ) was the standard Roman silver coin from its introduction in the Second Punic War to the reign of Gordian III (AD 238–244), when it was gradually replaced by the antoninianus. It continued to be minted in very ...

'' (an ancient Roman coin), and later used as the symbol of an old British penny (see

£sd £sd (occasionally written Lsd, spoken as "pounds, shillings and pence" or pronounced ) is the popular name for the pre-decimal currencies once common throughout Europe, especially in the British Isles and hence in several countries of the ...

History

In the Middle Ages, an

English penny The English penny (plural "pence"), originally a coin of pure silver, was introduced by King Offa of Mercia. These coins were similar in size and weight to the continental '' deniers'' of the period and to the Anglo-Saxon sceats which had p ...

's weight was literally, as well as monetarily, of an ounce and of a pound of

sterling silver Sterling silver is an alloy of silver containing 92.5% by weight of silver and 7.5% by weight of other metals, usually copper. The sterling silver standard has a minimum millesimal fineness of 925. '' Fine silver'', which is 99.9% pure silver, i ...

. At that time, the pound unit in use in England was the Tower pound, equal to 7,680 Tower grains (also known as wheat grains). The medieval English pennyweight was thus equal to 32 Tower grains. When Troy weights replaced Tower weights in 1527, the Troy weights were defined in such a way that the old Tower pound came out to exactly 5,400 Troy grains (also known as barleycorns), the Tower pennyweight Troy grains (and thus approximately 1.46 grams). After 1527, the English pennyweight was the Troy pennyweight. of 24 Troy grains. Thus the Troy pound, ounce, and pennyweight, with their definitions given in terms of the Troy grain instead of in terms of the Tower grain, were or 6.667% more than the Tower equivalents.

Usage

The troy pound and the pennyweight lost their official status in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...

in the

Weights and Measures Act A weights and measures act is a kind of legislative act found in many jurisdictions establishing technical standards for weights and measures. Notable acts of this type include: * Various Weights and Measures Acts (UK) or the various legislative ...

of 1878; only the troy ounce and its decimal subdivisions remained official. The troy ounce enjoys a specific legal exemption from

metrication Metrication or metrification is the act or process of converting to the metric system of measurement. All over the world, countries have transitioned from local and traditional units of measurement to the metric system. This process began in ...

in the UK. The pennyweight is the common weight used in the valuation and measurement of precious metals. Jewellers use the pennyweight in calculating the amount and cost of precious metals used in fabricating or casting jewellery. Similarly, dentists and dental labs still use the pennyweight as the measure of precious metals in dental crowns and inlays. Pennyweight and grains are still used to weigh gooseberries in competitions in

Cheshire Cheshire ( ) is a ceremonial and historic county in North West England, bordered by Wales to the west, Merseyside and Greater Manchester to the north, Derbyshire to the east, and Staffordshire and Shropshire to the south. Cheshire's county tow ...

, northwest UK. Over the

Pennines The Pennines (), also known as the Pennine Chain or Pennine Hills, are a range of uplands running between three regions of Northern England: North West England on the west, North East England and Yorkshire and the Humber on the east. Common ...

Yorkshire Yorkshire ( ; abbreviated Yorks), formally known as the County of York, is a Historic counties of England, historic county in northern England and by far the largest in the United Kingdom. Because of its large area in comparison with other Eng ...

the alternative drams and grains measurement has been used since a new set of scales was purchased by the Egton Bridge Old Gooseberry Society in 1937. As of 2018, the world record for the heaviest gooseberry of () was held by Kelvin Archer of Cheshire. The most common abbreviation for pennyweight is ''dwt''; ''d'', for the Roman ''

'', was the abbreviation for ''penny'' before Decimalisation of the British monetary system. Alternate abbreviations are ''pwt'' and ''PW''.

Uses unrelated to weight

Although the abbreviations are the same, the pennyweight bears no relation to the weight of the American penny nail. That name is derived from the price for a hundred nails in 15th century

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...

: the larger the nail, the higher the cost per hundred. The pennyweight also bears no relation to the weight of the American "

penny A penny is a coin ( pennies) or a unit of currency (pl. pence) in various countries. Borrowed from the Carolingian denarius (hence its former abbreviation d.), it is usually the smallest denomination within a currency system. Presently, it is t ...

" (1 cent) coin, which weighs 2.5 g (for those minted after 1982).

Conversion

References

{{Reflist Obsolete units of measurement Units of mass Customary units of measurement in the United States