Cyathus

Ancient RomanHistorical unit (no longer in standard use)Approximate value

One twelfth of a sextarius, about 45 mL. A small Roman ladle or wine cup.

1 cyathus = 0.04548611111 liters (approximately).

Approximate value. Standards for the cyathus varied by place and period, so this converter uses the most commonly cited value. Treat results as estimates, not exact figures.

About the cyathus

Greek kyathos, a cup or ladle, lies behind the Latin cyathus. In Roman use it was the small dipper for taking wine from a mixing bowl and filling drinking cups, so it served as the basic unit for serving rather than for trade. Wikipedia lists it as 1/72 of a congius, or 45 mL, the figure used here.

It appears in both the liquid and the dry tables, where it is one twelfth of a sextarius, so twelve cyathi filled the sextarius and 576 filled an amphora quadrantal. The unit therefore inherits the uncertainty of the sextarius, which scholars estimate at 500 to 580 mL from surviving vessels, putting a cyathus somewhere between about 42 and 48 mL. In modern terms it is a little over one and a half US fluid ounces, about the size of a shot glass or a generous tablespoon and a half.

Sources: Wikipedia: Ancient Roman units of measurement; Wikipedia: Cyathus (genus), on the Greek kyathos

Cyathus conversion chart

1 cyathus expressed in every other volume unit:

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