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Molecular Weight Calculator
Molecular Weight Calculator
Enter a chemical formula like H₂O, NaCl, C₆H₁₂O₆ to get the molar mass
MW = Σ(atomic weight × count) | units: g/mol
Use standard element symbols. Subscripts as numbers (H2O not H₂O).
Molar Mass
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in kg/mol
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in Da (u)
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1 mol = ? g
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ElementCountAtomic WtSubtotal
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About the Molecular Weight Calculator
Find the molecular weight (molar mass) of a compound from its chemical formula.
How to use the Molecular Weight Calculator
- Type the Chemical Formula, for example H2O, NaCl, C6H12O6 or H2SO4. Use capital letters correctly.
- Press Calculate Molecular Weight to see the mass and the breakdown by element.
Formula and method
Add the atomic mass of each atom in the formula, multiplying by the subscript. For example H₂O = 2 × 1.008 + 15.999 = 18.015 g/mol.
Worked example
NaCl = 22.990 + 35.45 = 58.44 g/mol. Glucose C₆H₁₂O₆ = 180.16 g/mol. Sulfuric acid H₂SO₄ = 98.08 g/mol.
Tips
- Element symbols are case-sensitive: Co is cobalt, CO is carbon monoxide.
- Use brackets for groups, such as Ca(OH)2.
Frequently Asked Questions
Numerically they are the same. Molar mass is expressed in g/mol, and molecular weight is a relative value.