A mole is a count — 6.022×10²³ of whatever is being counted. This converts between moles, mass in grams, and the actual number of particles, given a substance’s molar mass.
How it works
Moles, mass and particle count
grams = moles × molar mass · particles = moles × Avogadro’s number
Avogadro’s number is 6.02214076×10²³ per mole exactly — a defined value since the 2019 SI redefinition, not a measured constant with experimental uncertainty as it was before that.
A mole is a count, the same way “a dozen” is a count
This is the idea that trips newcomers up the most: a mole isn’t a chemistry-specific quantity of mass, or a unit tied to any one substance — it’s simply 6.022×10²³ of whatever is being counted. One mole of two different substances weighs two completely different amounts (their respective molar masses) while containing the exact same number of particles.
How to use this calculator
- Enter the substance’s molar mass — look it up, or use the molar mass calculator if you only have the formula.
- Choose whether you’re starting from moles or from a mass in grams.
- Read the mass, moles and particle count together.
Frequently asked questions
Why is Avogadro’s number the specific value it is?
It’s now a defined constant rather than a measured one — since 2019, the mole is defined so that Avogadro’s number is exactly 6.02214076×10²³, chosen to match the previous best experimental measurement as closely as possible so the change didn’t disrupt existing chemistry.
Why does 1 mole of different substances contain the same number of particles but weigh different amounts?
Because a mole counts particles, not mass — and different substances have different masses per particle (their molar mass), the same way a dozen large eggs and a dozen small eggs both contain twelve eggs but weigh different total amounts.
What counts as a “particle” here?
Whatever unit the substance is measured in — individual atoms for an element, molecules for a molecular compound, or formula units for an ionic compound. The calculator itself doesn’t distinguish; it reports the count of whatever unit corresponds to the molar mass entered.
Why is the particle count shown with zero decimal places?
Because a fractional particle has no physical meaning — the number is always an integer count in reality, even though the calculation itself involves a very large floating-point number.
Can I use this for a mixture rather than a pure substance?
Not directly — this assumes one substance with one molar mass. A mixture would need each component calculated separately.
