Empirical Formula Calculator

Find the simplest whole-number mole ratio of elements.

Element 1 mass % (%)

Element 1 atomic mass (g/mol)

Element 2 mass % (%)

Element 2 atomic mass (g/mol)

Element 3 mass % (%)

Element 3 atomic mass (g/mol)

Mole ratio 1 : 2 : 1

Formula: moles = % ÷ atomic mass, then ÷ smallest

Step-by-step with your numbers:

1. Values used:

2. Element 1 mass % = 40 %

3. Element 1 atomic mass = 12.011 g/mol

4. Element 2 mass % = 6.7 %

5. Element 2 atomic mass = 1.008 g/mol

6. Element 3 mass % = 53.3 %

7. Element 3 atomic mass = 15.999 g/mol

9. Mole ratio = 1 : 2 : 1

Did we solve your problem today?

Find the empirical (simplest) formula from elemental mass percentages.

The math behind it

Divide each element's % by its atomic mass to get moles, then divide all by the smallest to get the ratio.

C 40%, H 6.7%, O 53.3% → 1 : 2 : 1 (CH₂O).

Non-integer ratio?

Multiply all by a small whole number (e.g. ×2) to clear halves.