The amphora, or amphora quadrantal was a unit for measuring liquids or bulk goods in the Roman Empire

Roman Empire

The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....

, and for estimating the size of ships and the production of vineyards.

The volume of a standard amphora is equal to one cubic foot.

Thus the Roman amphora (one foot ~29.6 cm) contains about 26 litres, Greek amphoras varied from 18.5 L (pous italikos ~26.5 cm) to about 36 L (pous Ptolemaikos ~33.1 cm). The French amphora, also called the minot de Paris

Minot (unit)

The minot is an old unit of dry volume, used in France prior to metrication. The unit was equivalent to three French bushels , half a mine, and one quarter of a setier. The size of the minot is comparable to the US and Imperial bushels.The name minot derives from the larger unit, the mine, with...

, is 1/8 muid or one cubic pied du roi and therefore about 34 litres.

Along with other standard measures and the Roman currency

Roman currency

The Roman currency during most of the Roman Republic and the western half of the Roman Empire consisted of coins including the aureus , the denarius , the sestertius , the dupondius , and the as...

, it gave an added advantage to Roman commerce

Roman commerce

Roman trade was the engine that drove the Roman economy of the late Republic and the early Empire. Fashions and trends in historiography and in popular culture have tended to neglect the economic basis of the empire in favor of the lingua franca of Latin and the exploits of the Roman legions...

. A standard amphora, the amphora capitolina, was kept in the temple of Jupiter on the Capitoline Hill

Capitoline Hill

The Capitoline Hill , between the Forum and the Campus Martius, is one of the seven hills of Rome. It was the citadel of the earliest Romans. By the 16th century, Capitolinus had become Capitolino in Italian, with the alternative Campidoglio stemming from Capitolium. The English word capitol...

in Rome.