Grams to Moles Calculator

Created by Wojciech Sas, PhD candidate
Reviewed by Bogna Szyk and Jack Bowater
Last updated: Dec 02, 2020

With this grams to moles calculator, you can swiftly find how to calculate moles to grams for any substance. It can also work the other way around, as a grams to moles conversion tool! Read on to learn the grams to moles formula, try solving a problem of how to convert grams to moles yourself, and forget having any issues converting g to mol in the future!

How to calculate moles from grams? - Grams to moles formula

To correctly estimate the number of moles, n, of a substance of a specific mass, m, (in grams), you need to follow the grams to moles formula:

n = m / M,


  • M is the molar mass of this material. The unit is typically g/mol.

But wait, what actually is a mole? The mole is the SI unit of the measurement for the amount of a substance. In one mole of matter, there is precisely 6.02214085774 × 10²³ (using scientific notation) atoms, molecules, or anything else. This tremendous value refers to Avogadro's number. In other words, it's the unit of quantity, similarly as a dozen or a gross.

Anyway, that's quite a lot, isn't it? This is the reason why it's more convenient to know how to convert grams to moles instead of grams to the number of atoms. This grams to moles calculator helps you evaluate the right result in a fraction of a second.

How to use g to mol calculator?

The tool is really user friendly, and pretty straightforward to use:

  1. Pick one of the possible groups of compounds (you can choose one from Common Gases and Liquids, Salts, Acids, Alkali, Organic, or Pure Metals).

  2. Find the chemical of your desire from the second list. You can also enter any custom value for molar mass.

  3. Input the mass of your substance.

  4. ...And that's all! Our grams to moles calculator knows how to do its stuff!

  5. You can also find the total number of molecules (or atoms) in the Advanced mode.

How to convert grams to moles: an example

Take a look at the example of how to calculate moles from grams. Imagine you have 6 liters of pure water:

  1. Find the molar mass of a water molecule (H₂O). It's ca. 18.015 g/mol.

  2. Convert the volume of the water to its mass, assuming that the density of pure water is 998 kg/m³:

    m = 6 l * 998 kg/m³ = 0.006 m³ * 998 kg/m³= 5.988 kg.

  3. It's easier to work with grams, so convert the mass:

    5.988 kg = 5988 g.

  4. As you already know how the grams to moles conversion work, find the number of moles:

    n = 5988 g / 18.015 g/mol = 332.4 mol.

You can always use our grams to moles calculator to check the result!

Knowing how to convert grams to moles may be helpful in numerous chemical tasks, e.g., finding the mole fraction of a solution.

Wojciech Sas, PhD candidate
Choose one of the common chemicals or enter your own molar mass value
Common Gases and Liquids
Water (H₂O)
Molar mass
Grams to moles converter
Number of moles
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