Molar Mass Calculator — Molecular Weight

Molar mass is the bridge between the macroscopic world (grams, liters) and the molecular world (atoms, molecules, moles). It enables chemists to count molecules by weighing — a fundamental operation in all quantitative chemistry. The molar mass of a compound is the sum of the atomic masses of all its constituent atoms, weighted by their stoichiometric coefficients in the molecular formula.

Accurate molar mass calculation is essential for preparing solutions of known concentration, calculating reaction yields, determining empirical formulas from combustion analysis, interpreting mass spectrometry data, and designing pharmaceutical formulations. The periodic table provides atomic masses to four significant figures for most elements, giving molar masses accurate enough for virtually all practical purposes.

In polymer chemistry and biochemistry, molar mass becomes molecular weight — proteins are typically described by their mass in kilodaltons (kDa), where 1 Da = 1 g/mol. A typical protein might have a molecular weight of 50,000 Da (50 kDa). DNA, RNA, and polysaccharides also have molecular weights calculated by summing their monomer units' masses. Understanding molar mass is the starting point for all of analytical chemistry and biochemistry.