Molar mass calculator
Type a formula, brackets and hydrate dots included, like Ca(OH)2 or CuSO4·5H2O, and the molar mass appears in grams per mole, with each element's contribution and its share of the total.
The atomic weights are the standard IUPAC values, held in the page, so nothing you type is sent anywhere.
Case matters: Co is cobalt, CO is carbon and oxygen. Dots and brackets are fine.
98.072g/mol
| Element | Atoms | Atomic mass | Subtotal | Percent |
|---|---|---|---|---|
| OOxygen | 4 | 15.999 | 63.996 | 65.25% |
| SSulfur | 1 | 32.06 | 32.060 | 32.69% |
| HHydrogen | 2 | 1.008 | 2.016 | 2.06% |
Worked out in your browser from standard atomic weights. Nothing you type is sent anywhere.
Questions
- Is anything I type sent anywhere?
- No. Every tool here runs in the page itself. There is no server that receives your grades, your essay or your sources, and you can check it in your browser's network tab: using a tool produces no request carrying what you typed.
- Does it understand brackets and hydrates?
- Yes. Nested brackets like (NH4)2SO4 and hydrates written with a dot like CuSO4·5H2O or CuSO4.5H2O both work, with the coefficient after the dot applied to the water. It sums every element across the whole formula.
- Why does case matter?
- Because a symbol is one capital letter and up to one small one. Co is cobalt; CO is carbon then oxygen. Getting the case wrong is a common way to a confidently wrong answer, so the tool reads symbols exactly and flags anything that is not a real element.
- How accurate are the masses?
- They are the IUPAC standard atomic weights to four significant figures, which is plenty for school and undergraduate work. A few elements have no stable isotope, so their mass is the best-known isotope's mass number, and the tool says so when one appears in your formula.
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