Molar Mass Calculator
Type a chemical formula to get molar mass in g/mol. The page parses element symbols and parentheses, then sums IUPAC typical atomic weights. Also called molecular weight for covalent compounds.
Rated 4.9 out of 5 based on 412 reviews
How to compute molar mass from a formula
- Type the formula with standard element symbols and optional parentheses for groups.
- Use digits after a symbol or group for counts, such as H2O or Ca(OH)2.
- Read molar mass in g/mol, the parsed composition, and each element's contribution.
- Carry that molar mass into moles-to-grams or concentration work. Expand hydrate dots before pasting.
Molar mass
Mass per mole of a chemical formula
| Unit | g/mol |
|---|---|
| Atomic weight | IUPAC typical relative atomic mass for each element |
| Molecular weight | Same numeric value for a covalent molecule |
| Formula weight | Same approach for ionic formula units |
| Parentheses | Multiply a group, as in Ca(OH)2 |
| Composition | Element counts after parsing |
What molar mass reports
Molar mass is the mass of one mole of formula units. Glucose C6H12O6 is about 180.16 g/mol with the atomic weights on this page. Water H2O is about 18.015 g/mol.
Elements, groups, and formula units
Each capital letter starts an element symbol. Digits multiply that element. Parentheses wrap a group that a following digit multiplies. The formula unit is whatever the formula writes, molecule or ionic empirical unit.
How parsing works on this page
The engine walks the formula left to right, expands one level of parentheses, looks up each element in a standard atomic-weight table, and sums mass × count. Unknown symbols and mismatched parentheses throw clear errors.
Limits
Hydrates written with a middle dot are not accepted as one string. Expand them (for example CuSO4 plus five H2O) or type a known molar mass on the moles page. Atomic weights are typical IUPAC values, not a certificate of analysis. See the disclaimer.