Molar Mass Calculator
Find the molar mass of any compound from its chemical formula, with a per-element mass breakdown.
How it works
Molar mass = Σ (atomic mass of each element × number of atoms)
The molar mass of a compound is the sum of the atomic masses of every atom in its formula. The calculator parses the formula — including nested groups such as Ca(OH)₂ — counts each element, multiplies by the standard atomic weight, and adds the results. The answer is the mass in grams of one mole (6.022×10²³ formula units).
Worked example
For water, H₂O: two hydrogen atoms (2 × 1.008 = 2.016) plus one oxygen (15.999) gives a molar mass of 18.015 g/mol.
Sources: Molar mass — Wikipedia
Frequently asked questions
What is the difference between molar mass and molecular weight?
They are numerically the same value. Molecular weight is a dimensionless relative figure, while molar mass carries the unit g/mol — the mass of one mole of the substance.
How do I write a formula with brackets?
Type it as you would on paper: Ca(OH)2, Al2(SO4)3, and so on. The parser expands each group and multiplies the atoms inside by the subscript after the closing bracket.
Why does it reject my formula?
Symbols must use correct capitalisation — Co is cobalt but CO is carbon-plus-oxygen. An unrecognised symbol returns an "Unknown element" message so you can fix the case or spelling.
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