Molar mass is the mass of one mole of a substance, in grams per mole. It equals the sum of the atomic weights of all the atoms in the formula, and it is numerically the same as the molecular weight.

How do I type a formula?

Use correct capitalisation for element symbols, with a capital first letter, like Na or Cl, and numbers for the counts, like H2O. Brackets work too, such as Ca(OH)2 or Al2(SO4)3.

What is molar mass used for?

It converts between mass and moles, which is the first step in nearly every quantitative chemistry calculation, including making up solutions, balancing reactions and working out yields.

Molar Mass Calculator

This molar mass calculator works out the mass of one mole of a compound from its chemical formula, using the standard atomic weights of the elements. Molar mass, measured in grams per mole, is one of the most important numbers in chemistry, because it is the bridge between the mass you can weigh on a balance and the number of moles that chemical equations are written in. Almost every quantitative calculation, from making up a solution of known concentration to working out how much product a reaction can yield, starts by converting grams to moles using the molar mass. You type a chemical formula and the calculator adds up the atomic weight of every atom it contains. It reads correct chemical notation, so element symbols must be capitalised properly, with a capital first letter and a lower-case second letter where there is one, like Na, Cl or Mg, and subscript counts are written as ordinary numbers, as in H2O or C6H12O6. Brackets are supported for grouped units, so ammonium sulfate is entered as (NH4)2SO4 and aluminium sulfate as Al2(SO4)3. The result is the molar mass in grams per mole, which is numerically the same as the molecular weight in atomic mass units. Enter a formula to see its molar mass straight away.

Chemical formula

180.156 g/mol

molar mass of C6H12O6

Capitalise symbols correctly (Na, Cl, Ca). Brackets are supported, for example Ca(OH)2. Estimate only.

How it works

The calculator reads the formula one element at a time, multiplying each element's atomic weight by the number of those atoms, and adding the contribution of any bracketed group by its multiplier. The total is the molar mass. The atomic weights are the standard values used in chemistry.

Worked example

For glucose, C6H12O6, the calculator adds 6 carbons at 12.011, 12 hydrogens at 1.008 and 6 oxygens at 15.999. That comes to about 180.16 grams per mole.

Related calculators

Moles Calculator: mass to moles.
Molarity Calculator: concentration.
Dilution Calculator: dilute a stock.
pH Calculator: acidity and alkalinity.

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