Free · Stoichiometry calculators 🧪

Avogadro Atoms, Moles & Sample Mass

Convert between atom count, amount in moles and sample mass using the exact Avogadro constant and your entered molar mass.

  • Formula & worked example
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

One mole contains exactly 6.02214076 × 10²³ specified entities. A 24 g atomic sample with molar mass 12 g/mol contains 2 mol, or 1.204428152 × 10²⁴ atoms.

Atom count = Avogadro constant × amount in mol; mass in g = molar mass in g/mol × amount in mol

Worked example

Enter these known values and leave the other values blank.

Atomic sample mass
24 g
Atomic molar mass
12 g/mol
Amount of atoms
2 × 10⁰ mol
Number of atoms
120.44 × 10²² atoms

Assumptions and limitations

  • Use the molar mass of the same atomic species being counted. Counting atoms inside molecules also requires their stoichiometric multiplicity; this tool does not parse chemical formulas.
  • The Avogadro constant is fixed by SI at exactly 6.02214076 × 10²³ per mol. The constant field supports notation changes and consistent reverse solving; a different numerical constant is rejected.
  • Mass, amount and molar mass must be positive. Enter the coefficient in the selected power-of-ten unit: 1 in ×10²³ means 100,000,000,000,000,000,000,000 atoms.
  • Molar mass is an input, not a chemical lookup. Its measurement and isotope assumptions limit the precision of the result.

Common questions

Does one mole always weigh one gram?

No. One mole has the mass specified by its molar mass. A molar mass of 12 g/mol gives 12 g per mole.

References

Bookify validates the SI-defined Avogadro constant, allowing only decimal conversion tolerance at 6.02214076 × 10²³ per mol.

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