The litre or liter (see spelling differences)'s a unit of volume. There're two official symbols: the Latin letter L in lower and upper case (l and L). The lower case L's also often written as a cursive ℓ, though this symbol has no official approval by any international bureau. Although the litre isn't an SI unit, it's accepted for use with the SI, and has appeared in several versions of the metric system. The official SI unit of volume's the cubic metre (m3). One litre's equal to 0.001 cub… (More on Liter)