Number of Atoms in a Mole Calculator

Formula used

For a substance with chemical formula F and amount n moles:

• Molecules: N = n × N_A
• Atoms per element i: A_i = n × N_A × a_i, where a_i is the count of element i in one formula unit.
• Total atoms: A_total = n × N_A × Σ a_i

N_A = 6.022 140 76 × 10²³ mol⁻¹ (exact).

How to use this calculator

1. Enter moles and the chemical formula (e.g., Ca3(PO4)2, CuSO4·5H2O).
2. Click Compute to see molecules, per‑element atoms, and totals.
3. Choose notation and precision to format very large values.
4. Use Download CSV or Download PDF to save results.

Avogadro’s constant — quick facts

• Exact value: N_A = 6.022 140 76 × 10²³ mol⁻¹.
• Since 2019 SI redefinition, this value is exact by definition.
• Links the macroscopic mole to the number of microscopic entities.
• Works for atoms, molecules, ions, or formula units as applicable.

Quick reference: atoms per molecule and per mole

“Atoms in 1 mole” updates with the current Avogadro value and formatting.

Diatomic elements at standard conditions

These exist as two‑atom molecules; one mole contains twice N_A atoms:

Monatomic noble gases: He, Ne, Ar, Kr, Xe, Rn, Og.