Molar mass calculator
Type a formula such as C6H12O6 or CuSO4·5H2O to get its molar mass in g/mol and the share of each element. Built for students and lab work.
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How to use it
- Enter chemical formula.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Molar mass M = sum of (atom count × IUPAC standard atomic weight) over all elements; element mass % = its mass in the formula ÷ M × 100.
Example
Inputs: Chemical formula = CuSO4·5H2O. Result: Molar mass: 249.677 g/mol; Atoms per formula unit: 21.
CuSO4·5H2O
CuH10O9S
Limits and caveats
- Uses IUPAC abridged standard atomic weights; a real sample can differ slightly because natural isotope mixes vary.
- Symbols are case-sensitive: Co is cobalt, CO is carbon monoxide.
Questions about this tool
How do I enter a hydrate such as copper sulfate pentahydrate?
Type CuSO4·5H2O, CuSO4*5H2O or CuSO4.5H2O. The number after the dot multiplies the whole water molecule.
Is molar mass the same as molecular weight?
They have the same number. Molar mass is in g/mol, while molecular mass is in atomic mass units (u or Da).
Can I use nested brackets?
Yes. Ca3(PO4)2 and K4[Fe(CN)6] both work, and the number after a bracket multiplies everything inside it.