Conversion from 50 Hundredweights to Grams

Information about the Hundredweight (cwt)

The hundredweight is a unit of mass whose value depends on which side of the Atlantic you are standing. The imperial or long hundredweight is 112 pounds, about 50.802 kilograms. The US or short hundredweight is 100 pounds, about 45.359 kilograms. Its symbol is cwt, from the Latin centum and the English weight.

The name promises a hundred and the imperial version delivers a hundred and twelve, which looks like an error until the arithmetic behind it is seen. Twenty hundredweight make a long ton of 2240 pounds, and a hundredweight is eight stone of fourteen pounds each. The chain of halvings and doublings that runs from the pound to the ton only closes neatly if the intermediate unit is 112, so the number is a consequence of the system rather than a mistake in it.

Its working life was in bulk trade. Coal, cement, grain, potatoes and fertiliser moved by the hundredweight, and sack sizes were built around it: the standard British coal sack held one hundredweight, which is why a coal merchant's cart was rated in a number of hundredweight rather than in tons. Vans and light trucks were once classified the same way, and the phrase survives in some vehicle names.

In the United States the short hundredweight is still used in agricultural markets, where livestock, grain and milk prices are quoted per hundredweight rather than per pound or per ton. Elsewhere the unit has largely given way to the tonne and the kilogram, and its main modern role is to make old records intelligible.

Continental Europe kept a cousin of it under a different name. The quintal, from the Arabic qintar by way of medieval Latin, served the same purpose in French, Spanish, Italian and Portuguese trade, and when the metric system arrived it was simply redefined as a round 100 kilograms. That metric quintal is still the unit in which grain harvests are reported across much of southern Europe, Latin America and India, and it sits close enough to the imperial hundredweight of 50.8 kilograms that old and new figures can look deceptively similar. The parallel is instructive: both units survived because a sack a strong worker could handle is a more natural quantity than any round metric mass.

One imperial hundredweight equals 112 pounds, about 50.802 kilograms, or 8 stone.

Information about the Gram (g)

The gram is a unit of mass equal to one thousandth of a kilogram. Its symbol is g. Although the kilogram is the SI base unit, the gram is the one that carries the prefixes, so milligram and microgram are built on the gram rather than on the kilogram.

That awkwardness is historical. The original metric system of 1795 defined the gramme as the mass of one cubic centimetre of water at the temperature of melting ice. It was intended as the base unit, but a one-gram standard is too light to be a practical reference: a speck of dust or a fingerprint changes it measurably. The thousandfold-larger kilogram was made the standard artefact instead, and the SI inherited the arrangement, leaving the base unit as the only one carrying a prefix in its own name.

Cooking outside the English-speaking world runs on grams, and increasingly inside it as well. Weighing flour rather than measuring it by volume removes the largest source of error in baking, because a cup of flour can vary by twenty per cent depending on how it was packed. Professional bakers work entirely in grams and express recipes as percentages of flour weight.

Nutrition panels report protein, fat, carbohydrate, sugar and fibre in grams, so the unit is the everyday currency of dietary arithmetic. Postal services price letters and small parcels in grams, and precious metals, though traded in troy ounces, are sold to the public in gram bars.

It is also the unit the SI prefixes attach to, which is why the system has a base unit that already carries a prefix. Smaller and larger masses are named from the gram and never from the kilogram: a thousandth of a gram is a milligram, not a microkilogram, and a million grams is a megagram, better known as the tonne. The rule spares the language a set of double prefixes that would otherwise be unavoidable, but it leaves the kilogram in the odd position of being the only base unit whose name contains one. Postal tariffs show the gram at work in ordinary life: letter rates step at 20, 50 and 100 grams, and a sheet of office paper weighs about five.

One gram equals 0.001 kilograms, one thousand milligrams, or about 0.035 ounces.