Grams to Moles Calculator

A mole is chemistry's counting unit — it represents 6.022 × 10²³ particles of a substance, and converting grams to moles is one of the most common calculations in chemistry. Enter your substance's mass (in grams) and molar mass (in g/mol) — or pick from presets like Water, Glucose, or Sodium Chloride — to get the number of moles, the number of individual molecules, and the formula used. Also try the calculate Result, Efficiency Rating & Actual Yield — Percent Yield.

g

Enter the mass of the substance in grams

g/mol

Enter the molar mass of the substance in g/mol

Select a common substance or choose custom to enter your own molar mass

Results

Number of Moles

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Number of Molecules

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Formula Used

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Frequently Asked Questions

How to calculate moles from grams?

To calculate moles from grams, use the formula: n = m / M, where n is the number of moles, m is the mass in grams, and M is the molar mass in g/mol. Simply divide the mass by the molar mass to get the number of moles. See also our Stoichiometry Calculator.

What is molar mass and how do I find it?

Molar mass is the mass of one mole of a substance, typically expressed in g/mol. You can find it by adding up the atomic masses of all atoms in the molecular formula using the periodic table. For example, water (H₂O) has a molar mass of 18.015 g/mol.

How many moles are 100 grams of water?

Using the formula n = m / M, with 100 grams of water and water's molar mass of 18.015 g/mol: n = 100 g ÷ 18.015 g/mol = 5.551 mol. So 100 grams of water equals approximately 5.55 moles.

Can this calculator work backwards from moles to grams?

Yes, you can rearrange the formula to m = n × M. If you know the number of moles and molar mass, multiply them to get the mass in grams. Our calculator shows the relationship between all three values. You might also find our calculate Converted Value, Conversion Factor Used & Scientific Notation — u to Grams Converter useful.

What is Avogadro's number and how does it relate to moles?

Avogadro's number is 6.022 × 10²³, representing the number of atoms, molecules, or particles in one mole. This means one mole of any substance contains exactly this many particles, making it a bridge between atomic scale and measurable quantities.

Why is the mole concept important in chemistry?

The mole allows chemists to count atoms and molecules by weighing them. It provides a way to relate the microscopic world of atoms to macroscopic measurements like mass, making chemical calculations and stoichiometry possible.

What are common mistakes when converting grams to moles?

Common mistakes include using incorrect molar mass values, forgetting to account for all atoms in a compound, mixing up units, and not properly calculating molecular formulas. Always double-check your molar mass calculations and ensure units are consistent.