What is Avogadro's number?

Avogadro's number (Nₐ) is 6.02214076×10²³. It defines the number of particles (atoms, molecules, ions, etc.) in one mole of a substance, as set by the 2019 SI redefinition of the mole.

How do I find the molar mass?

For a pure element, use its atomic mass from the periodic table (e.g. carbon = 12.011 g/mol). For a compound, sum the atomic masses of all atoms in the formula (e.g. H₂O = 2×1.008 + 15.999 = 18.015 g/mol).

What is the formula used?

Number of particles N = n × Nₐ, and mass m = n × M, where n is moles, Nₐ is Avogadro's number, and M is molar mass in g/mol. All three fields are derived from these two equations.

Does this work for molecules as well as atoms?

Yes. Avogadro's number applies equally to atoms, molecules, ions, or any countable particle. Just ensure your molar mass matches the particle type you are counting (atomic mass for atoms, molecular weight for molecules).

Why does my input show scientific notation?

The number of particles in typical lab quantities is enormous (e.g. 1 mol = 6.02×10²³). The calculator displays large or small numbers in scientific notation automatically for readability.

Avogadro Number Calculator

Name: Avogadro Number Calculator
Availability: InStock
Author: Nham Vu

Convert between moles, number of particles, and mass using Avogadro's number (6.02214076×10²³).

Enter Values

Fill in the molar mass and any one quantity. The other two are calculated automatically.

Molar Mass (g/mol)

Required for mass conversions. Leave blank if working with moles ↔ particles only.

Enter one of the three quantities below

Moles (mol)

Number of Particles

Mass (grams)

Requires molar mass to calculate.

Results

Moles

—

mol

Number of Particles

—

atoms / molecules / ions

Mass

—

grams

Constants Used

Avogadro's number (Nₐ): 6.02214076 × 10²³ mol⁻¹
Formulas: N = n × Nₐ
m = n × M

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Summary

Convert between moles, number of particles, and mass using Avogadro's number (6.02214076×10²³).

How it works

Enter the molar mass of your substance (g/mol) — find it on the periodic table or from the molecular formula.
Type a value in any one of the three fields: moles, number of particles, or mass (grams).
The calculator derives the other two values using N = n × Nₐ and m = n × M.
All three results update in real time as you type.
Use the swap button to reset inputs and start a new calculation.

Use cases

Convert moles of a substance to the number of atoms or molecules.
Find how many moles are in a given mass of a compound.
Calculate the mass of a specific number of molecules.
Verify stoichiometry calculations in chemistry homework.
Quickly cross-check lab measurements for titrations or reactions.
Teach or demonstrate Avogadro's constant in classroom exercises.

Frequently Asked Questions

Last updated: 2026-06-18 · Reviewed by Nham Vu