Molar Mass Calculator
Type a chemical formula and get its molar mass with the full breakdown: how many atoms of each element, their atomic masses from the periodic table, and the total. Understands parentheses and hydrates with a dot.
Breakdown
| Element | Atoms | Atomic mass | Contribution, g/mol |
|---|
How it is computed. The molar mass of a substance is the sum of the atomic masses of all atoms in its formula. Atomic masses come from the periodic table and are multiplied by the atom counts: for H2SO4 that is 2 hydrogens, 1 sulfur, and 4 oxygens. Numerically the molar mass in g/mol equals the relative molecular mass.
FAQ
What is molar mass in simple words?
It is the mass of one mole of a substance — 6.02·10²³ particles — in grams. The calculation is simple: add up the atomic masses of all atoms in the formula. For water H2O it is 2 · 1.008 + 16 = 18.02 g/mol.
How do formulas with parentheses work, e.g. Ca(OH)2?
The index after the parenthesis multiplies everything inside: Ca(OH)2 has two OH groups, i.e. 2 oxygens and 2 hydrogens plus calcium. Total: 40.08 + 2 · (16.00 + 1.008) = 74.1 g/mol.
How are hydrates like CuSO4·5H2O handled?
The dot means “plus”: add the mass of five water molecules to the mass of CuSO4. The number before H2O multiplies the whole water molecule, not just the hydrogen.
Why are atomic masses not whole numbers?
Because elements occur in nature as mixtures of isotopes with different masses. The periodic table lists the weighted average: chlorine, for example, is 35.45 — a blend of isotopes 35 and 37.
Free online molar mass calculator from a chemical formula. Enter the formula and the calculator breaks it into atoms, shows the atomic mass of each element from the periodic table, every element's contribution, and the total in g/mol.
Parentheses with indices are supported — Ca(OH)2, Al2(SO4)3 — as well as hydrates with a dot: CuSO4·5H2O. The dot can be typed as ·, or *. The breakdown is laid out as a table, the way chemistry homework requires for amount-of-substance problems.
Everything is computed in the browser; nothing is sent to a server. Useful for chemistry classes, students, and lab work — anywhere you need a quick molar mass with a visible breakdown.