Molecular Weight Calculator

What is Molecular Weight?

Molecular weight (also called molar mass) is the mass of one mole of a substance, expressed in grams per mole (g/mol). It's calculated by summing the atomic masses of all atoms in the molecular formula.

How to Write Chemical Formulas

• Element symbols: Use proper capitalization (H, C, O, Na, Cl, etc.)
• Numbers: Write subscript numbers normally (H2O, not H₂O)
• Parentheses: Use for groups that repeat - Ca(OH)2 means one Ca, two O, and two H
• Order: Typically written as C, H, then other elements alphabetically

Common Compounds

• Water: H2O = 18.015 g/mol
• Salt: NaCl = 58.443 g/mol
• Glucose: C6H12O6 = 180.156 g/mol
• Sulfuric Acid: H2SO4 = 98.079 g/mol
• Calcium Hydroxide: Ca(OH)2 = 74.093 g/mol
• Ethanol: C2H5OH = 46.069 g/mol

Applications

• Converting between grams and moles in stoichiometry
• Preparing solutions of specific molarity
• Determining empirical and molecular formulas
• Calculating percent composition of elements
• Analyzing chemical reactions and yields

You can embed this util on your own site as a widget. Adding ?embed=1 to the URL loads a compact version with just the tool itself; no header, menu, or documentation. Paste this snippet into your HTML:

Copy snippet Adjust the height to taste.