Molecule Count Calculator Formula

Understand the math behind the molecule count calculator. Each variable explained with a worked example.

Formulas Used

Number of Molecules

num_molecules = (mass_grams / molar_mass) * 6.022e23

Moles

moles = mass_grams / molar_mass

Variables

VariableDescriptionDefault
mass_gramsMass of Compound(g)18
molar_massMolar Mass(g/mol)18.015

How It Works

How to Count Molecules

Formula

N = (mass / molar mass) × 6.022 × 10^23

Worked Example

How many molecules in 18 g of water?

mass_grams = 18molar_mass = 18.015
  1. 01Moles = 18 / 18.015 = 0.999 mol
  2. 02Molecules = 0.999 × 6.022 × 10^23 ~ 6.02 × 10^23

Ready to run the numbers?

Open Molecule Count Calculator