The Equivalent weight of the acid is the number of parts by mass of the acids which contains 1.008 parts by mass of replaceable hydrogen. Equivalent Mass is the amount of substance that combines with or displaces 8.0 g of oxygen (or 1.008 g of hydrogen), usually expressed in grams. Use this online equivalent weight of an acid calculator to estimate the result from the molecular weight and basicity of an acid. Enter the molecular weight and basicity of acid to know the result.