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Molar Mass Calculator

Calculate molar mass instantly from any chemical formula. Get an element-by-element breakdown, supports nested parentheses and hydrates, using IUPAC 2024 atomic masses online.

Updated June 2026

Molar mass

18.015 g/mol

ElementAtomsAtomic massContribution%
O115.99915.99988.8%
H21.0082.01611.2%

Atomic masses from IUPAC 2024 CIAAW abridged table. Tip: paste this molar mass into the molarity calculator to compute concentration from grams.

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What it does

Type a chemical formula and get the molar mass with a per-element breakdown. Supports nested parentheses, hydrate dots (CuSO4·5H2O), and leading coefficients. Atomic masses are IUPAC 2024 abridged values.

Drop the result into the molarity calculator to convert grams ↔ moles. For dilutions, use the dilution calculator.

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How to use it

  1. Type the formula — capitalization matters (Co ≠ CO).
  2. Use parentheses for repeated groups: (NH4)2SO4.
  3. Use · or * for hydrates: CuSO4·5H2O.
  4. Click a sample for a starting point.

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