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 is the reference unit for volume on this site.

About the liter

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.

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

Liter conversion chart

1 liter expressed in every other volume unit:

More Metric (SI) units

• milliliter (volume)
• cubic meter (volume)
• cubic centimeter (volume)
• cubic millimeter (volume)
• microliter (volume)
• centiliter (volume)
• deciliter (volume)
• hectoliter (volume)
• meter (length)
• kilometer (length)
• centimeter (length)
• millimeter (length)
• micrometer (length)
• nanometer (length)
• picometer (length)
• decimeter (length)

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