Mass percent, also known as weight percent, is a unit of concentration that indicates the amount of solute in a given volume of solution. The quantity of solute is expressed in mass or by moles. For a solution, the mass per cent is described as the grams of solute per grams of solution, multiplied by 100 to get the percentage.

Mass percent is commonly used in laboratory experiments and analytical chemistry to determine the amount of a substance present in a sample or solution.