Calculators
Molecular Weight Calculator
Find the molar mass of a chemical formula.
FreeNo sign-upWorks in your browser
Case-sensitive element symbols (e.g. Co ≠ CO). Supports parentheses.
Molecular weight (molar mass)
180.156 g/mol
About the Molecular Weight Calculator
Enter a chemical formula — like H2O, C6H12O6, or Ca(OH)2 — and the calculator returns its molecular weight (molar mass) in grams per mole, summing the standard atomic weights of each element. It supports parentheses and is a must-have for chemistry stoichiometry and lab work.
How to use the Molecular Weight Calculator
- 1Enter your a chemical formula.
- 2Read the result instantly — it recalculates as you type.
- 3Adjust the numbers to model different scenarios.
Frequently asked questions
What is molecular weight?
The sum of the atomic weights of all atoms in a molecule, in grams per mole. Water (H2O) is about 18.02 g/mol.
How do I write a formula?
Use element symbols with correct capitalization (Co is cobalt, CO is carbon monoxide) and numbers for counts. Parentheses like Ca(OH)2 work too.