Molecular Weight Calculator
Calculate the molecular mass (g/mol) and elemental percentage composition of chemical formulas using official IUPAC standard atomic weights.
Calculator Inputs
Supports standard chemical symbols, subscripts, parentheses, and LaTeX syntax (e.g., H_2SO_4).
- Molecular Weight (Molar Mass)
- 180.16
- Elemental Mass Composition
- C: 40.00%, H: 6.71%, O: 53.28%
- Unique Elements Count
- 3
- Interpretation
- Valid formula: C6H12O6
About these results
CalcSpectrum calculators produce automated estimates using established formulas and the specific values you enter. Because real-world outcomes depend on input accuracy, mathematical assumptions, and rounding conventions, please verify critical figures with an appropriately qualified financial, tax, medical, legal, or other professional, as relevant.
How It's Calculated
Formula
Molecular weight (or molar mass) is the sum of the atomic masses of all atoms present in a given chemical formula, measured in grams per mole (g/mol) or daltons (Da). Standard atomic weights are established by IUPAC and the Commission on Isotopic Abundances and Atomic Weights (CIAAW).
Worked Examples
Sulfuric Acid (H2SO4) Molar Mass
- Hydrogen (H): 2 atoms × 1.008 g/mol = 2.016 g/mol.
- Sulfur (S): 1 atom × 32.06 g/mol = 32.06 g/mol.
- Oxygen (O): 4 atoms × 15.999 g/mol = 63.996 g/mol.
- Total molecular weight = 2.016 + 32.06 + 63.996 = 98.072 g/mol.
Frequently Asked Questions
What units are used for molecular weight?
Molecular weight is typically expressed in grams per mole (g/mol), which is numerically identical to unified atomic mass units (u) or Daltons (Da).
Can I enter formulas with parentheses?
Yes. Formulas with parentheses and group multipliers like Ca(OH)2 or (NH4)2SO4 are fully supported.
Where do the atomic weight values come from?
All atomic weights are sourced from the Commission on Isotopic Abundances and Atomic Weights (CIAAW) under the International Union of Pure and Applied Chemistry (IUPAC).