Calculator
Use n = m / M. Enter a molar mass in g/mol.
Formula and assumptions
n = m / M; particles = n × Nₐ
A mole links an amount of substance to its mass through molar mass. The particle count uses the exact Avogadro constant, 6.02214076 × 10²³ mol⁻¹.
Assumption: The supplied molar mass represents the substance being calculated.
Variables and units
Worked example
For 18.015 g of water with a molar mass of 18.015 g/mol, n = 1.000 mol.
From grams to particles
| Sample | Molar mass | Moles | Particles |
|---|---|---|---|
| 18.0 g water | 18.015 g/mol | 0.999 | 6.017e+23 molecules |
| 10.0 g sodium chloride | 58.44 g/mol | 0.171 | 1.030e+23 formula units |
| 1.00 g carbon | 12.011 g/mol | 0.083 | 5.014e+22 atoms |
The Avogadro constant is exactly 6.02214076 × 10²³ per mole since the 2019 SI redefinition. Use the molar mass of the whole formula: oxygen gas is O₂ at 32.00 g/mol, not O at 16.00 g/mol, so 32 g of oxygen gas is one mole of molecules but two moles of atoms.
Important limits
The calculator does not identify a compound or validate its formula or molar mass.
Reference and related tools
IUPAC: amount of substance. Return to Chemistry Calculators for the other tools in this group.