Molar Mass Calculator
Calculate the molar mass of a compound by entering atom counts for up to 9 common elements using IUPAC standard atomic weights.
Results
What is it?
Molar mass (g/mol) is the mass of one mole (6.022 x 10^23 molecules) of a compound. It equals the sum of atomic masses of all atoms in the molecular formula, using IUPAC 2021 standard atomic weights.
How to use
Enter the number of atoms of each element in your molecule. For glucose (C6H12O6): C=6, H=12, O=6 -- giving 180.156 g/mol. Set all unused elements to 0.
Example scenario
Aspirin (C9H8O4): C=9, H=8, O=4 -> 9x12.011 + 8x1.008 + 4x15.999 = 108.099 + 8.064 + 63.996 = 180.159 g/mol. ATP (C10H16N5O13P3): C=10, H=16, N=5, O=13, P=3 -> 507.181 g/mol.
Pro tip
Molar mass is used to convert between grams and moles: moles = mass(g) / molar mass. For ionic compounds, use the formula unit mass. Note: these are monoisotopic masses averaged over natural isotope abundances -- mass spectrometry uses monoisotopic masses instead. For proteins, divide molecular weight (Da) by 1000 to get kDa.