What is it?
The Molar Mass Calculator works out the molar mass of a chemical formula such as H2SO4. It shows each element’s share, and if you add a mass, the number of moles and molecules.
Who is it for?
Chemistry students from Class 9 to college, lab staff and teachers.
How to use it
Type the formula, e.g. H2O, Ca(OH)2, C6H12O6, CuSO4.5H2O. Optionally enter a Mass (optional, to find moles) in grams. The answer appears as you type; there is no Calculate button. Tap Copy result to copy it, or Share on WhatsApp to send it.
Writing formulas
- Capital letters matter:
Cois cobalt,COis carbon monoxide. - Brackets multiply everything inside: Ca(OH)2 has 2 O and 2 H.
- “Write hydrates with a dot: CuSO4.5H2O”
- Don’t write charges or states, like (aq) or ²⁺.
Data used
It uses IUPAC standard atomic weights. Textbooks sometimes round (Cl = 35.5, O = 16), so answers may differ slightly in the decimals.
Moles and molecules
Moles = mass ÷ molar mass. 18 g of water is 1 mole, which is 6.022 × 10²³ molecules (Avogadro’s number). For solutions, continue with the Molarity & Dilution Calculator.
Worked example
H2SO4 = 2(1.008) + 32.06 + 4(16.00) ≈ 98.08 g/mol; 49 g is 0.5 mol.
Errors and how to fix them
- Cannot read “…”: check capital letters (Co vs CO).
- “A bracket is not closed” or “A closing bracket has no opening one”
Open the tool: Molar Mass Calculator
Still stuck?
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Questions, or an error not listed here?
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