Molar Mass and Molecular Weight Calculator
Adds up the atomic weights in a formula.
Molar mass
— g/mol
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
Formula read as —
Atoms per formula unit —
By element
Reading this —
The formula
molar mass = Σ (atomic weight × atoms in the formula)
Brackets multiply everything inside them. A dot adds a separate part, as in a hydrate.
What to watch out for
Molecular weight and molar mass are the same number. Molar mass has units of g/mol; molecular weight is the same figure in unified atomic mass units, or as a plain ratio.
Frequently Asked Questions
What is the molar mass of calcium hydroxide?
Ca(OH)₂ is 74.092 g/mol: one calcium, two oxygen and two hydrogen.
How are hydrates entered?
With a dot and the count: CuSO4.5H2O gives 249.677 g/mol, which includes the water.
Is molecular weight the same as molar mass?
Numerically, yes. Water is 18.015 in both: g/mol for the molar mass, and u per molecule for the molecular weight.