Molar Mass Calculator
Formula weight and mass percentRuns locally · nothing uploaded
Examples
Atomic weights
Formula weight
249.677
Molar mass
249.677 g/mol
| Element | Atoms | Atomic weight | Subtotal | Mass % |
|---|---|---|---|---|
| Cu Copper | 1 | 63.546 | 63.546 | 25.45% |
| S Sulfur | 1 | 32.06 | 32.06 | 12.84% |
| O Oxygen | 9 | 15.999 | 143.991 | 57.67% |
| H Hydrogen | 10 | 1.008 | 10.08 | 4.04% |
25 g = 0.10013 mol
Also works as:molar mass calculatormolecular weight calculatorpercent compositiongrams to moles
How it works
Formula
Molar mass = Σ(atomic weight × count)Mass % = element mass ÷ molar mass × 100%Worked example
Given: H2SO4
- 2 × 1.008 + 32.06 + 4 × 15.999 = 98.072.
Result: 98.07 g/mol; S ≈ 32.69%.
Sources
- IUPAC standard atomic weights (2021 abridged)
How to use
- 1Type the formula (case-sensitive).
- 2Choose standard or rounded weights.
- 3Read molar mass and mass percent.
FAQ
Molar mass vs formula weight?
Same number; molar mass is in g/mol.
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