Avogadro’s Number Calculator

Convert moles to the number of particles (atoms, molecules, or ions) using Avogadro’s number, or work backward from mass to particle count.

Calculation Mode

Amount

mol

Number of Particles

particles

Mass of Sample

Molar Mass

g/mol

What This Calculator Does

Avogadro’s number (6.02214076 × 10²³) is the number of atoms, molecules, ions, or other elementary particles contained in exactly one mole of a substance. This calculator converts between moles and particle count, or works from a sample’s mass to tell you how many particles it contains.

The Formula

The core relationship is Number of Particles = moles × N_A, where N_A is Avogadro’s number. To go the other way, divide the particle count by N_A to get moles. When starting from mass, moles are first found using moles = mass ÷ molar mass, then multiplied by N_A to get the particle count.

A Few Notes

“Particles” refers to whatever discrete unit the substance is made of — atoms for an element, molecules for a molecular compound, or formula units/ions for an ionic compound.
Because Avogadro’s number is so large, results for even small mole amounts will be very large numbers.
This calculator is intended for general chemistry education and reference purposes.

Last reviewed August 2026