Molar Mass Calculator
Calculate the molar mass of a compound from its chemical formula.
Enter a formula such as H2O, C6H12O6, NaCl, or Ca(OH)2. Element symbols are case-sensitive.
Molar Mass
Per-Element Breakdown
What Is Molar Mass?
The molar mass of a substance is the mass of one mole of that substance, expressed in grams per mole (g/mol). It is numerically equal to the molecular weight (or formula weight) in atomic mass units. To find it, you add up the atomic masses of every atom in the chemical formula.
M = Σ (atomic mass × number of atoms)
How to Read a Chemical Formula
Each element is written with its symbol (one uppercase letter, optionally followed by a lowercase letter), and the subscript number after it gives how many atoms of that element are present. A missing subscript means one atom. Parentheses group atoms together, and the number after a closing parenthesis multiplies everything inside the group.
- • H2O — 2 hydrogen atoms and 1 oxygen atom
- • NaCl — 1 sodium atom and 1 chlorine atom
- • C6H12O6 — 6 carbon, 12 hydrogen, and 6 oxygen atoms
- • Ca(OH)2 — 1 calcium plus 2 of each O and H inside the group
Worked Examples
| Compound | Formula | Molar Mass (g/mol) |
|---|---|---|
| Water | H2O | 18.015 |
| Table salt | NaCl | 58.44 |
| Glucose | C6H12O6 | 180.156 |
| Calcium hydroxide | Ca(OH)2 | 74.092 |
Note: This calculator uses standard atomic weights for a curated set of common elements. Results are based on average isotopic abundances and may differ slightly from values that use full-precision IUPAC atomic weights or specific isotopes. For analytical work, verify the atomic masses against the latest IUPAC recommendations.