Decaliter (daL)

The decalitre is a unit of volume equal to ten litres. Its symbol is daL, and the spelling dekalitre is also accepted. It sits between the litre of the household and the hectolitre of the trade, and although it once had a settled place in European markets it is now among the least written of the metric volume units.

Its historical role was as a physical measure rather than a number. Nineteenth-century French markets sold grain, potatoes, chestnuts and dried beans out of stamped cylindrical vessels holding one decalitre, half a decalitre or a double one, and a trader's set of these was inspected and verified like a set of weights. Selling dry goods by volume was faster than weighing them and needed no balance, so the vessels did real work.

Weighing displaced it. Once cheap accurate scales became universal, dry goods moved to mass, which is fairer to the buyer because it does not depend on how densely a load happens to settle. The decalitre lost its purpose along with the practice, and the vessels survive in museums and in the vocabulary of a few older markets rather than in commerce.

The quantity itself remains perfectly ordinary. Ten litres is a large household bucket, half a jerrycan, the fuel tank of a scooter, or a fortnight of drinking water for one person. It is roughly the volume of a cubic vessel twenty-two centimetres on a side, and it weighs ten kilograms when filled with water.

What killed the unit as a written form was the same pressure that removed deca everywhere else. Metric practice steps by factors of a thousand, so litres serve until about a thousand of them and hectolitres take over for trade quantities. Ten litres is written 10 L, which is shorter than 1 daL, needs no explanation, and sorts correctly beside 5 L and 200 L in the same table.

When the unit does appear, usually in an old record or a translated document, the conversion is a single step. Multiply by ten for litres, divide by ten for hectolitres, and the resulting figure will match modern usage without any loss of precision.

One decalitre equals 10 litres, 0.1 hectolitres, about 2.64 US gallons, or about 2.2 imperial gallons.

Decaliter conversion table