Liquid Measures

The grain measure (modius) was used for dispensation of both dry goods and liquids. Whether it was used to measure out grain, olive oil or wine, the standard applied was a simple one. The contents of three modii would fill one amphora. Thus:

1 Italian modius is equivalent to 18.2 U.S. pints [8.62 liters].

1 amphora is equivalent to about 6.84 U.S. gallons [25.9 liters].

During the Republican and early Imperial eras, the amphora was the standard for calculating cargo burdens in the seaborne trade of wine. There were several other measures, however, that were used in both the wholesale and retail aspects of wine in the Roman economy. In the vineyard it was the culleus (strictly translated, the sown-up skin of an ox) and in the tavern it was the cyathus, which nominally was the capacity of a wine ladle.

In between the culleus and the cyathus lay the most commonly used domestic measure for both dry and wet goods, the sextarius, which is equivalent to about 0.14 U.S. gallons [0.54 liters].

Roman literature also refers to the dolium,the massive, pear-shaped jar into which the unfermented wine juice was decanted directly from the wine press's vats. The dolium was not a standard measure, however; surviving examples range in capacity anywhere from 10 to 65 amphorae. Massive wooden casks (cupae) seem to have been used in much the same way as dolia and to have been just as variable in size.