Mole Calculator
Fill in the mass or the moles, and enter the molar mass.
This result is an estimate only. Double-check important figures before relying on them.
How it is calculated
- Moles = mass ÷ molar mass
- Mass = moles × molar mass
- Particles = moles × 6.02214076 × 10²³
For concentration, use the molarity calculator.
Worked example
18 g of water (molar mass 18.015 g/mol):
- Moles = 0.99917 mol
- Molecules = 6.0171 × 10²³
Why your number may differ
Atomic masses are rounded, and different tables use slightly different values. For exam work, use the values your course gives.
Frequently asked questions
What is a mole?
A mole is 6.02214076 × 10²³ particles, such as atoms or molecules. It lets chemists count particles by weighing.
How do I convert grams to moles?
Divide the mass by the molar mass. 18 g of water, with a molar mass of 18.015 g/mol, is about 1 mole.
Where do I get the molar mass?
Add the atomic masses of every atom in the formula using the periodic table. For example H₂O is 2 × 1.008 + 15.999.