Molecular Weight Calculator
Molar Mass from Chemical Formula
Molecular Weight
Ready for Calculation
Enter a chemical formula (e.g. NaCl, H2O, Ca(OH)2) to calculate its molecular weight.
Understanding Molecular Weight
Molecular weight (also called molar mass) is the sum of the atomic weights of every atom in a molecule's chemical formula, expressed in grams per mole (g/mol). It's a foundational value for converting between mass and moles in any chemistry calculation.
Reading Chemical Formulas
Element symbols are followed by a subscript count when more than one atom is present (H2O = 2 hydrogen, 1 oxygen). Parentheses group repeated units, like Ca(OH)2 meaning one calcium plus two hydroxide groups.
Why It Matters
Molecular weight bridges the microscopic (individual molecules) and the measurable (grams on a scale), letting chemists weigh out exact numbers of moles for any reaction.
Feeds Directly Into Molarity
Once you know a compound's molecular weight, you can plug it directly into our Molarity Calculator along with a target mass and volume to prepare a solution of known concentration.
Example: Glucose
C6H12O6 (glucose) has a molecular weight of about 180.16 g/mol — 6 carbons, 12 hydrogens, and 6 oxygens summed together.
Key Takeaways
- Case-Sensitive Symbols: Chemical symbols are case-sensitive — "Co" is cobalt, while "CO" is carbon monoxide.
- Nested Parentheses Supported: Formulas with grouped subunits, like Ca(OH)2 or Al2(SO4)3, are fully supported.
- Standard Atomic Weights: Calculations use standard atomic weights (average across natural isotope abundance), matching typical periodic table values.