Molecular Weight Calculator

Calculate the molecular weight (molar mass) of any chemical compound or formula.

Enter the chemical formula using proper notation (e.g., H2O, C6H12O6). Note: Element symbols must use proper capitalization (H, not h; Na, not NA or na).

How to Use

  • Enter a chemical formula using proper notation (e.g., H2O, NaCl, Ca(OH)2)
  • For compounds with parentheses, use proper nesting: Ca(OH)2
  • Select the number of decimal places for the result
  • Click "Calculate Molecular Weight" to get the result

Common Examples

Water (H2O)

Molecular Weight: 18.015 g/mol

Glucose (C6H12O6)

Molecular Weight: 180.156 g/mol

Sodium Chloride (NaCl)

Molecular Weight: 58.443 g/mol

Calcium Hydroxide (Ca(OH)2)

Molecular Weight: 74.093 g/mol

About Molecular Weight

Molecular weight, also known as molecular mass or molar mass, is the mass of a molecule. It is calculated as the sum of the atomic weights of each constituent element multiplied by the number of atoms of that element in the molecular formula.

The molecular weight is expressed in atomic mass units (amu) or grams per mole (g/mol). One mole of a substance contains Avogadro's number (6.022 × 1023) of molecules.

This calculator uses the most recent atomic weight values from the International Union of Pure and Applied Chemistry (IUPAC).

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