Molar Mass Calculator

Calculate molecular weight and element composition from any chemical formula instantly.

Molecular Weight Calculator for Chemical Formulas

A molecular weight calculator finds the formula mass of a compound by adding the atomic masses of every element in its chemical formula. For example, H2O contains two hydrogen atoms and one oxygen atom, so its molecular weight is about 18.016 g/mol.

Use for molecular weight

Enter formulas like C6H12O6, NaCl, H2SO4 or Ca(OH)2 to calculate formula mass.

Use for molar mass

The numeric result is also the molar mass in g/mol, useful for mole and stoichiometry problems.

Use for percent composition

The element breakdown shows how much each element contributes to the total formula mass.

AI Answer Summary

How do you calculate molecular weight?

Molecular weight is calculated by multiplying each element's atomic mass by the number of atoms in the formula, then adding those values together. Molar mass has the same numeric value as molecular weight but is expressed in grams per mole (g/mol).

Formula

Molar mass = sum of atomic mass x atom count for each element.

Use cases

Convert grams to moles, prepare solutions and check percent composition.

Input notes

Use standard chemical formulas with element symbols, numbers and parentheses.

Frequently Asked Questions About Molar Mass

What is molar mass?

Molar mass is the mass of one mole of a substance, measured in grams per mole (g/mol). It's numerically equal to the molecular weight of a compound. For example, the molar mass of water (H₂O) is 18.016 g/mol.

How do you calculate molar mass?

To calculate molar mass:

  1. Identify each element in the chemical formula
  2. Find the atomic mass of each element
  3. Multiply atomic mass by the number of atoms
  4. Sum all the values

Example: H₂O = (2 × 1.008) + (1 × 15.999) = 18.015 g/mol

Can this calculator handle complex formulas?

Yes! This calculator handles:

  • Simple compounds (NaCl)
  • Parentheses (Ca(OH)₂)
  • Multiple parentheses (Ca₃(PO₄)₂)
  • Hydrates (CuSO₄·5H₂O)
  • Large organic molecules (C₆H₁₂O₆)

Why do I need to know molar mass?

Molar mass is essential in chemistry for:

  • Stoichiometric calculations (determining reactant/product amounts)
  • Preparing solutions with specific concentrations
  • Understanding chemical reactions
  • Laboratory work and experiments
  • Academic chemistry courses

What units can I get results in?

This calculator provides results in three units:

  • g/mol - Grams per mole (standard)
  • lb/mol - Pounds per mole (US customary)
  • kg/kmol - Kilograms per kilomole (metric)

Is this calculator free to use?

Yes! This molar mass calculator is completely free and requires no registration. Calculations are performed instantly in your browser.