Molar Mass Calculator
Enter any chemical formula — simple (H2O), with parentheses (Ca(OH)2, Fe2(SO4)3), or a hydrate (CuSO4·5H2O) — to get its molar mass and a per-element mass breakdown, calculated from current standard atomic weights.
Try:
Molar mass: 249.691 g/mol
Swipe to see every column →
| Element | Count | Atomic mass | Subtotal | Mass % |
|---|---|---|---|---|
| O Oxygen | 9 | 15.999 | 143.991 | |
| Cu Copper | 1 | 63.55 | 63.550 | |
| S Sulfur | 1 | 32.07 | 32.070 | |
| H Hydrogen | 10 | 1.008 | 10.080 |
How it works
The calculator parses your formula into atom counts per element — handling nested parentheses/brackets and hydrate notation (separated by ·, * or .) — then multiplies each element's atom count by its standard atomic weight and sums the results. Mass percent shows how much each element contributes to the compound's total mass, which is the basis for empirical formula and percent composition calculations.