atoms
Enter a positive number of atoms.
Enter in standard notation (e.g. 3.011e23) or scientific (3.011×10²³ = 3.011e23)
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Sources & Methodology
Avogadro’s number: 6.02214076 × 10²³ mol−¹ as defined by the 2019 SI redefinition. Mole formula per IUPAC and NIST standards.
NIST — SI Redefinition: Avogadro Constant
National Institute of Standards and Technology reference for the exact value of Avogadro's constant (6.02214076 × 10²³ mol−¹) used in all calculations on this page, as defined in the 2019 SI revision.
IUPAC Gold Book — Avogadro Constant
International Union of Pure and Applied Chemistry definition of the Avogadro constant and the mole as the SI base unit for amount of substance, confirming the formula used in this calculator.
Atoms to Moles: Moles = Number of Atoms ÷ 6.02214076 × 10²³
Moles to Atoms: Atoms = Moles × 6.02214076 × 10²³
Avogadro’s Number (Nₐ): 6.02214076 × 10²³ mol−¹ (exact, defined since 2019)
Moles to Atoms: Atoms = Moles × 6.02214076 × 10²³
Avogadro’s Number (Nₐ): 6.02214076 × 10²³ mol−¹ (exact, defined since 2019)
⏱ Last reviewed: April 2026
How Are Atoms Converted to Moles?
The mole is the SI unit for amount of substance. It bridges the atomic scale (individual atoms, too small to count directly) with the laboratory scale (grams, which can be weighed). Avogadro’s number defines exactly how many atoms are in one mole: 6.02214076 × 10²³.
The Atoms to Moles Formula
Moles = Number of Atoms ÷ Nₐ
Atoms = Moles × Nₐ
Nₐ = 6.02214076 × 10²³ mol−¹ (Avogadro’s constant)
Example: How many moles are in 1.806 × 10²&sup4; atoms?
Moles = 1.806 × 10²&sup4; ÷ 6.022 × 10²³ = 3.0 moles
Moles = 1.806 × 10²&sup4; ÷ 6.022 × 10²³ = 3.0 moles
Common Mole Conversions Reference
| Moles | Number of Atoms | Scientific Notation |
|---|---|---|
| 0.1 mol | 60,221,407,600,000,000,000,000 | 6.022 × 10²² |
| 0.5 mol | 301,107,038,000,000,000,000,000 | 3.011 × 10²³ |
| 1 mol | 602,214,076,000,000,000,000,000 | 6.022 × 10²³ |
| 2 mol | 1,204,428,152,000,000,000,000,000 | 1.204 × 10²&sup4; |
| 5 mol | 3,011,070,380,000,000,000,000,000 | 3.011 × 10²&sup4; |
| 10 mol | 6,022,140,760,000,000,000,000,000 | 6.022 × 10²&sup4; |
What Is Avogadro’s Number?
Avogadro’s number (Nₐ = 6.02214076 × 10²³) is the number of elementary entities in one mole. It was chosen so that 1 mole of any element equals its atomic mass in grams — making lab measurements practical. For example: 1 mole of carbon (atomic mass 12) weighs exactly 12 grams and contains 6.022 × 10²³ carbon atoms.
Atoms vs Molecules vs Moles
The mole applies to any particle: atoms, molecules, ions, or electrons. For molecules, note that each molecule contains multiple atoms. For example, 1 mole of water (H&sub2;O) contains 6.022 × 10²³ water molecules but 1.807 × 10²&sup4; total atoms (3 atoms per molecule × 6.022 × 10²³).
💡 Memory Trick: Think of the mole like a “dozen” for chemistry. Just as a dozen always means 12, a mole always means 6.022 × 10²³. The difference is that atoms are so tiny we need an astronomically large number to work with practical lab quantities. Avogadro’s number makes atomic-scale chemistry measurable on a bench-top scale.
Frequently Asked Questions
Moles = Number of Atoms ÷ Avogadro’s Number (6.022 × 10²³). Example: 1.806 × 10²&sup4; atoms ÷ 6.022 × 10²³ = 3 moles. Avogadro’s number is the bridge between the atomic and macroscopic scales in chemistry.
Atoms = Moles × Avogadro’s Number (6.022 × 10²³). Example: 2.5 moles × 6.022 × 10²³ = 1.5055 × 10²&sup4; atoms. This works for any element or compound.
Avogadro’s number is 6.02214076 × 10²³ mol−¹. Since the 2019 SI redefinition it is an exact defined value, not a measured approximation. It represents the number of elementary entities in one mole of any substance, named after Italian scientist Amedeo Avogadro.
Exactly 6.02214076 × 10²³ atoms. This is Avogadro’s number. So 1 mole of carbon has 6.022 × 10²³ carbon atoms. 1 mole of iron has 6.022 × 10²³ iron atoms. The number of atoms per mole is the same for every element.
2 moles × 6.022 × 10²³ = 1.2044 × 10²&sup4; atoms. Simply multiply the number of moles by Avogadro’s number. For 3 moles: 3 × 6.022 × 10²³ = 1.8066 × 10²&sup4; atoms.
A mole is the SI base unit for amount of substance. One mole contains exactly 6.02214076 × 10²³ elementary entities. The mole is designed so that 1 mole of any element equals its atomic mass in grams — making 1 mole of carbon = 12 g, 1 mole of water = 18 g, and so on.
One mole of molecules contains 6.022 × 10²³ molecules (same Avogadro’s number). But each molecule contains multiple atoms. 1 mole of water (H&sub2;O) = 6.022 × 10²³ molecules but 1.807 × 10²&sup4; total atoms (3 per molecule).
Moles = Mass (g) ÷ Molar Mass (g/mol). Example: 36 g of water (molar mass 18 g/mol): 36 ÷ 18 = 2 moles. Then atoms: 2 × 6.022 × 10²³ = 1.2044 × 10²&sup4; atoms. Use this calculator for the moles ↔ atoms step after calculating moles from mass.
Moles = Atoms ÷ (6.022 × 10²³). Conversely: Atoms = Moles × (6.022 × 10²³). These two reciprocal formulas are all you need to convert between atoms and moles in any chemistry calculation.
0.5 × 6.022 × 10²³ = 3.011 × 10²³ atoms. This is exactly half of Avogadro’s number. Any fraction of a mole gives a proportional fraction of Avogadro’s number of atoms.
Atoms are incredibly tiny — a carbon atom has a mass of about 2 × 10−²³ grams. Avogadro’s number is large because it bridges atomic mass units (amu) with grams. One mole of carbon (6.022 × 10²³ atoms) weighs exactly 12 grams, making atomic-scale chemistry practical in the lab.
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