Molecular weight calculator
Compute molar mass from a chemical formula, including hydrates.
Runs in your browser
Molar mass
Enter a formula to calculate.
Formula
M = Σ (atomic weight × atom count)ModelIUPAC 2021 abridged standard atomic weights
- Standard atomic weights of the elements 2021 — Pure and Applied Chemistry, 2021
Calculated in your browser. Nothing you entered was sent anywhere.
Values follow IUPAC’s current abridged atomic weights, so a result may differ from a supplier’s catalogue in the last digit. Ammonium sulfate, for instance, comes to 132.13 here against the 132.14 printed on most bottles — the difference is sulfur.
About this tool
Parse a chemical formula and sum standard atomic weights to give molar mass in g/mol. Nested groups and hydrates are supported, so formulae can be pasted straight from a supplier catalogue.
Related tools
- Molarity calculator — Convert between mass, molar concentration and volume for a solution.
- Dilution calculator — Work out how much stock and diluent to combine for a target concentration.
Science last reviewed .