Mole Calculator
Convert mass to moles and number of particles.
Results update as you type.
How it works
The mole is the chemist's unit for counting particles, and this mole calculator converts a measured mass into the number of moles and the number of individual particles it contains. You enter the mass of your sample and the molar mass of the substance, and it returns the amount in moles and the particle count using Avogadro's number. The mole bridges the gap between the grams you can weigh in the lab and the atoms or molecules that actually react, which is why it sits at the heart of stoichiometry. One mole of any substance contains the same number of particles, roughly 602 sextillion, and its mass in grams equals the substance's molar mass, found by adding the atomic masses in its formula. Students use this conversion constantly to prepare solutions, balance reaction amounts, and interpret experimental data, and it is a foundational skill in every chemistry course. Because the calculation depends only on mass and molar mass, it works for elements, compounds, and ions alike. Enter the mass and molar mass to get both the moles and the particle count instantly.
n = mass / molar mass; particles = n × Nₐ
The number of moles equals the mass of a sample divided by the molar mass of the substance, because the molar mass is the mass of exactly one mole. Multiplying the moles by Avogadro's number, about 6.022 times ten to the twenty-third, converts the amount into the actual count of atoms, molecules, or formula units in the sample, since one mole always contains that many particles.
Source:Chemistry (the mole concept)
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Worked example
How to use this calculator
- 1
Enter your values
Enter mass and molar mass.
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Amount updates instantly as you type — no button to press.
Frequently asked questions
What is a mole in chemistry?
A mole is the SI unit for the amount of a substance, defined as exactly 6.02214076 times ten to the twenty-third particles. It lets chemists count atoms and molecules by weighing, because one mole of a substance has a mass in grams equal to its molar mass. The mole connects the microscopic world of particles to measurable laboratory quantities.
How do I convert grams to moles?
Divide the mass in grams by the molar mass in grams per mole. For example, 36 grams of water divided by its molar mass of about 18 grams per mole gives 2 moles. The molar mass comes from adding the atomic masses of every atom in the chemical formula. This calculator performs the division and also returns the particle count.
What is Avogadro's number?
Avogadro's number is 6.02214076 times ten to the twenty-third, the number of particles in exactly one mole of any substance. Multiplying the moles by this constant gives the total count of atoms, molecules, or ions in a sample. It is one of the fundamental constants of chemistry and defines the scale that links moles to individual particles.
How do I find the molar mass?
Add up the atomic masses of all the atoms in the substance's chemical formula, using the values from the periodic table. For water, H₂O, that is two hydrogen atoms at about 1.008 plus one oxygen at about 16.00, giving roughly 18.02 grams per mole. Enter that molar mass into the calculator along with your sample's mass.
Does this work for elements and compounds?
Yes. The mole calculation is identical whether you are working with an element like iron, a molecular compound like glucose, or an ionic compound like sodium chloride. You only need the correct molar mass for whatever substance you have. The calculator does not care about the chemical identity; it simply divides mass by molar mass and applies Avogadro's number.