What is Avogadro's number?

6.022 × 10²³ particles per mole. One mole of carbon-12 has exactly 12 grams and 6.022 × 10²³ atoms.

Molar Mass Calculator — Chemical Formula

Calculate molar mass of any compound from its chemical formula. Includes molecular weight, elemental percentages, and worked examples.

18.015g/mol

Molar mass of H2O ≈ 18.015 g/mol

Element	Count	Mass (g/mol)	%
H	2	2.016	11.2%
O	1	15.999	88.8%
Total			18.015 g/mol

Molar mass formula: Sum the atomic masses of all atoms in the formula. For H₂O: 2×1.008 + 15.999 = 18.015 g/mol. Molar mass (g/mol) is the mass of one mole of a substance; molecular weight (Da or amu) is the mass of one molecule — numerically they are equal.

How Molar Mass Is Calculated

The molar mass of a compound is the sum of the atomic masses of every atom in its chemical formula. Each element contributes its standard atomic weight (in g/mol) multiplied by the number of times it appears in the formula. For example, water (H₂O) contains two hydrogen atoms (2 × 1.008) and one oxygen atom (15.999), giving 18.015 g/mol. The calculator parses the formula — including subscripts, parentheses, and hydration water — and sums these contributions automatically.

Molar mass is the bridge between the microscopic world of atoms and the macroscopic world of the laboratory. It lets you convert between mass in grams and amount in moles, which is essential for preparing solutions, balancing reactions, and performing stoichiometric calculations.

Molar Mass vs. Molecular Weight

Molar mass (g/mol) is the mass of one mole of a substance, while molecular weight (in daltons or atomic mass units) is the mass of a single molecule. Because one mole contains Avogadro's number (6.022 × 10²³) of particles, the two values are numerically equal — one mole of water weighs 18.015 grams and one water molecule has a mass of 18.015 Da.

How It Works

Calculate molar mass of any compound from its chemical formula. Includes molecular weight, elemental percentages, and worked examples

Each component has a specific meaning:

Its chemical formula — The its chemical formula recorded for the scenario being assessed.

Note: Interpret the molar mass result against the thresholds and context described above.

How to Use

Enter the its chemical formula for the scenario you are assessing. Calculate molar mass of any compound from its chemical formula. Includes molecular weight, elemental percentages, and worked examples. Use the molar mass result to inform your calculation.

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