Equivalent Weight Calculator

About this calculator

The equivalent weight of a substance is its molar mass divided by its valence factor (n-factor) — the number of replaceable H⁺ ions for an acid, OH⁻ ions for a base, or the number of electrons transferred for a redox reagent. It represents the mass of a substance that supplies or reacts with exactly one mole of “reacting unit” (one proton, one hydroxide, or one electron).

It's the basis of normality (N = molarity × n-factor), still widely used in acid-base and redox titrations because equivalents react in exact 1:1 ratios regardless of the compound's stoichiometry. Chemistry students and laboratory technicians use equivalent weight to prepare normal solutions and calculate titration endpoints, especially for polyprotic acids and multivalent redox reagents where molarity alone can be misleading. Enter the molar mass and valence to get the equivalent weight.