Molar Mass Calculator
Type a chemical formula and get its molar mass in g/mol, with every element's contribution shown.
Molar mass
180.156g/mol
Distinct elements
3
| Element | Atoms | Atomic weight | Subtotal |
|---|---|---|---|
| C | 6 | 12.011 | 72.066 g/mol |
| H | 12 | 1.008 | 12.096 g/mol |
| O | 6 | 15.999 | 95.994 g/mol |
How it works
Molar mass is the weight of one mole of a substance — Avogadro's number of molecules — measured in grams per mole. To find it, you add up the atomic weight of every atom in the formula. Water, H2O, comes out to about 18.015 g/mol: two hydrogens at 1.008 plus one oxygen at 15.999.
Type the formula the way a chemist writes it. Element symbols are one capital letter, sometimes followed by a lowercase one (Na, Cl, Ca). A number right after a symbol multiplies just that element, and parentheses group things — so Ca(OH)2 means one calcium and two OH units, giving 74.09 g/mol.
The table underneath shows each element, how many atoms of it the formula contains, its atomic weight, and the subtotal. That makes it easy to double-check the math or see which element dominates the mass — in glucose, C6H12O6, carbon and oxygen carry most of the weight.
Frequently asked questions
What formulas can I enter?
Anything built from element symbols, subscripts, and parentheses — H2O, NaCl, C6H12O6, Ca(OH)2, CuSO4, and so on. It handles one or more levels of parentheses. Charges, dots for hydrates, and state labels aren't parsed, so leave those out.
Are these average atomic weights?
Yes. The calculator uses standard atomic weights, which are averages over an element's natural isotope mix. That's what you want for ordinary chemistry. If you need the mass of a specific isotope, you'd use that isotope's mass instead.
Why does capitalization matter?
Because symbols are case-sensitive. 'Co' is cobalt, but 'CO' is carbon plus oxygen. Write each element with a capital first letter and a lowercase second letter so the parser reads it the way you mean.