Congii to Liters (congius to L)

1 congius equals 3.275 liters exactly.

1 congius = 3.275 liters

How to convert congii to liters

To convert congii to liters, multiply the number of congii by 3.275. This factor is exact. To go the other way, multiply liters by 0.3053435115 (rounded).

liters = congii × 3.275

Example: 10 congii = 32.75 liters.

Pints, quarts, gallons and fluid ounces differ between the US and the UK. Units are labeled 'US' or 'imperial' to avoid confusion.

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

About these units

Congius (congius)

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

Six sextarii, about 3.27 L. A Roman liquid measure a little under a US gallon.

Eight congii made up one amphora quadrantal, and each congius was defined as a cube measuring half a Roman foot on each side. Wikipedia's table gives it as 3.27 L, which is the figure used here. The cube definition links it directly to the length standard, so any doubt about the exact length of the pes carries straight into the volume.

Inside the liquid scale, the congius was divided into 6 sextarii, and further down into 72 cyathi. Larger vessels such as the culeus were counted in congii, with 160 of them to the culeus. Because it came to roughly 3.3 L, it sits near the modern US gallon of 3.785 L, though it is noticeably smaller. Surviving vessels never match each other exactly, and the sextarii they imply range between 500 and 580 mL, so a congius from archaeology could fall anywhere from about 3.0 to 3.5 L.

1 congius = 3.275 liters (approximately).

Sources: Wikipedia: Ancient Roman units of measurement

Liter (L)

Metric (SI)Current unit

One cubic decimeter (1,000 cm³). The everyday metric unit of volume for drinks, fuel and cooking.

The liter was born in revolutionary France. In 1795 it was introduced as a republican unit and defined as one cubic decimeter, while the gram was tied to a cubic centimeter of water. The name comes from the older French litron, itself descended from a Byzantine Greek unit of weight, not volume. A small revision of the decimeter in 1798 left the first liter about 1.000974 of today's cubic decimeter, and in 1879 the international metric authorities adopted the liter with the symbol l.

The liter then took a strange detour. In 1901 it was redefined as the space taken up by one kilogram of pure water at its densest, which made it about 1.000028 cubic decimeters, and that muddled definition lasted until 1964, when it was restored to exactly one cubic decimeter. A capital L was added as an alternative symbol in 1979 because a lowercase l is easy to mistake for the digit 1, and NIST says L is the symbol to use in the United States. A liter of water is close to a kilogram, which is why a one-liter bottle feels like a kilo in the hand.

The liter is the reference unit for volume on this site.

Sources: Wikipedia: Litre; NIST Guide to the SI, Chapter 5: units outside the SI

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