Milliliters are not equal to grams. mL is a unit of volume, grams are a unit of mass, and mass = volume * density.

Milliliter is a unit of volume. mL is milliliter, the unit of measure. When the unit of measurement is expressed in letters, the general situation unit symbol letters in lowercase; when the unit is derived from a person's name, the first letter of the symbol must be capitalized. Only the volume unit "liter" special, this symbol can be written as a capital L, but also can be written as a lowercase l.

This is because the "liter" symbol is the earliest lowercase, due to the lowercase l and the Arabic numerals 1 is difficult to distinguish, and then the International General Assembly of Weights and Measures Later, the International Conference on Weights and Measures resolved that the symbol for "l" could be written in uppercase L, so that in the case of lowercase not yet abolished, both upper and lower case were used.

This is the only symbol in the International System of Units (SIU) that is not derived from the name of a scientist and can be capitalized. The letter "m" for milli (10^-3) is not to be confused with the letter "M" for megagram (10^6), as required by the International System of Units.

Density is a measure of mass in a given volume, density is equal to the mass of an object divided by its volume, and can be expressed by the symbol ρ (pronounced rho), the International System of Units (SI units) and Chinese legal units of measurement, the density of the unit of kilograms per cubic meter, the symbol is kg/m3.