Which atomic weights does this use?

It uses IUPAC conventional standard atomic weights (2021), the same values printed on most periodic tables, so results match textbook answers.

Can it handle brackets and hydrates?

Yes. Parentheses and square brackets with multipliers work, for example Ca(OH)2 or Al2(SO4)3. Write a hydrate like CuSO4.5H2O as CuSO4(H2O)5 for an exact parse.

Is anything uploaded?

No — the formula is parsed entirely in your browser and nothing leaves your device.

Molar Mass Calculator

Molar mass of any chemical formula, with per-element breakdown.

Molar mass calculator

The molar mass of a compound is the mass of one mole of it, in grams per mole (g/mol). It is the sum of the standard atomic weights of every atom in the chemical formula.

Type a formula such as C6H12O6 (glucose) or Ca(OH)2 (calcium hydroxide) and this tool parses the elements, multiplies each by its IUPAC atomic weight, and shows the total plus a per-element breakdown — instantly, in your browser.