One milliliter is equal to one one-thousandth of a liter or 1 cubic centimeter. In U.S. measurements, a milliliter is 0.03 fluid ounces, 0.06 cubic inches or 0.2 teaspoons; in British Imperial units, a milliliter is 0.04 fluid ounces or 0.17 teaspoons. There are roughly 15 to 20 drops of a liquid in 1 milliliter.

The milliliter is part of the metric system, a standardized decimal-based form of measurement first proposed in the 16th century and widely adopted by scientists and international organizations in the 19th century. The liter was intended to measure the volume of water with a mass of 1 kilogram.