The hundredweight or centum weight (abbreviated cwt) is a unit of mass defined in terms of the pound
Pound (mass)
The pound or pound-mass is a unit of mass used in the Imperial, United States customary and other systems of measurement...

 (lb). The definition used in Britain differs from that used in North America. The two are distinguished by the terms long hundredweight and short hundredweight:
  • The long hundredweight is defined as 112 lb, which is equal to 50.802345 kg. This is the definition used in the imperial system
  • The short hundredweight is defined as 100 lb, which is equal to 45.359237 kg. This is the definition used in the US customary system
    United States customary units
    United States customary units are a system of measurements commonly used in the United States. Many U.S. units are virtually identical to their imperial counterparts, but the U.S. customary system developed from English units used in the British Empire before the system of imperial units was...

    . This is also the usual hundredweight in Canada. The short hundredweight is also called a cental, especially in places which normally use the long hundredweight.

Under both conventions, there are twenty hundredweight in a ton
The ton is a unit of measure. It has a long history and has acquired a number of meanings and uses over the years. It is used principally as a unit of weight, and as a unit of volume. It can also be used as a measure of energy, for truck classification, or as a colloquial term.It is derived from...

, the long ton
Long ton
Long ton is the name for the unit called the "ton" in the avoirdupois or Imperial system of measurements, as used in the United Kingdom and several other Commonwealth countries. It has been mostly replaced by the tonne, and in the United States by the short ton...

being 2,240 lb and the short ton
Short ton
The short ton is a unit of mass equal to . In the United States it is often called simply ton without distinguishing it from the metric ton or the long ton ; rather, the other two are specifically noted. There are, however, some U.S...

being 2,000 lb.

The long and short hundredweight are both descended from the French avoirdupois
The avoirdupois system is a system of weights based on a pound of 16 ounces. It is the everyday system of weight used in the United States and is still widely used to varying degrees by many people in Canada, the United Kingdom, and some other former British colonies despite the official adoption...

 weight system, which became established in England in Late Medieval times. British custom came to widely use the stone weight, which is 14 pounds, and wished for the hundredweight to be a whole number of stones (and 100 is not a multiple of 14). The stone was not one of the avoirdupois units in Medieval France, and never became customary in the British American colonies or the USA. In 1824 in the UK, new weights and measures legislation made it illegal for merchants to use the word hundredweight in the sense of a hundred pounds. A merchant could be sued for fraud for doing so. In 1879, the hundred pound weight was re-legalized for trade in the UK under the name "cental", in response to legislative pressure from UK merchants who were importing corn and tobacco from the USA.

The short hundredweight is commonly used in USA in the sale of livestock
Livestock refers to one or more domesticated animals raised in an agricultural setting to produce commodities such as food, fiber and labor. The term "livestock" as used in this article does not include poultry or farmed fish; however the inclusion of these, especially poultry, within the meaning...

 and some cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...

 grains and oilseeds, paper
Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....

, and concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

 additives and on some commodities in futures exchange
Futures exchange
A futures exchange or futures market is a central financial exchange where people can trade standardized futures contracts; that is, a contract to buy specific quantities of a commodity or financial instrument at a specified price with delivery set at a specified time in the future. These types of...

s A few decades ago, commodities weighed in terms of long hundredweight included cattle, cattle fodder, fertilizers, coal, some industrial chemicals, other industrial materials, and so on, but since the adoption of the metric system by all English-speaking countries apart from the USA, it is now hardly used other than by church bell ringers but church bell manufacturers are increasingly moving over to the metric system. Before the 15th century in England, a hundredweight was a different unit equal to 108 lb.
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