Volume of a liter - or liter?

Answer 1

One litre may equal:

1000ml, 1,000,000ul, 1,000,000,000nl, 1,000,000,000,000pl, 0.001m3

A litre is already a unit of volume. In fact it is the scientific unit of preference (deemed to be an SI unit)
1 litre (liter) is a measure of volume equal to 1,000 ml or 1,000 cm3.

Answer 2

A liter is a unit of volume equal to 1,000 cubic centimeters or 1 cubic decimeter. It is commonly used to measure liquid volumes, such as in beverage containers.