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Calcimator

Molecular Weight Calculator

Calculate the molecular weight (molar mass) of chemical compounds from their formula. Shows element-by-element breakdown with atomic weights.

Inputs

Results

Molecular Weight

18.015 g/mol

Chemical FormulaH2O
Total Atoms3
Unique Elements2
Element BreakdownH: 2 Γ— 1.008 = 2.016 g/mol (11.2%) O: 1 Γ— 15.999 = 15.999 g/mol (88.8%)
How to Use This Calculator
  1. Select a compound from the list (water, NaCl, glucose, CO2, etc.) or enter a custom formula.
  2. Review the element-by-element breakdown showing atomic weight and count for each element.
  3. Check total molecular weight in g/mol.
  4. Use molecular weight to convert between grams and moles in stoichiometry calculations.
  5. Remember: molecular weight in g/mol equals the mass of one mole of that substance.
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Formula

Molecular Weight = Sum of (atomic weight Γ— count) for each element. Atomic weights from IUPAC 2021 standard values.

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