Gram per liter

The gram per liter, symbol g/L or g·L^-1, is a unit of measurement of mass concentration, which is used to indicate how many grams of a certain substance are present in a liter of mixture, usually liquid or gas. This unit does not belong to the International System, since it refers to the liter, which does not belong to said system. In SI, the unit of mass concentration is the kilogram per cubic meter, which is numerically equivalent: 1 g/L = 1 kg/m³.

Often SI prefixes are applied, giving rise to units such as milligram per liter (mg/L) or microgram per deciliter (μg/dL). For measurements of concentrations in water, the expression "part per million" (ppm) can be used, since a liter of pure water weighs, under normal conditions, one kilogram, or one million milligrams. Likewise, in the expression of the graduation of an alcoholic beverage, the similar milliliter per liter (mL/L) is used.