Molecular Formula Calculator
Find the molecular formula from an empirical formula and the compound's molar mass.
Molecular Formula
C₆H₁₂O₆
- Empirical formula
- CH₂O
- Empirical formula mass
- 30.026 g/mol
- Molar mass
- 180.16 g/mol
- Multiplier
- ×6
Calculation working
How it was calculated
CH₂O = 12.011 + 2(1.008) + 15.999
= 30.026 g/mol
180.16 ÷ 30.026 ≈ 6
(CH₂O)₆ = C₆H₁₂O₆
What is a molecular formula?
A molecular formula shows the actual number of atoms of each element in one molecule. An empirical formula shows only the simplest whole-number ratio.
Empirical formula: CH₂O → Molecular formula: C₆H₁₂O₆
Both have the same ratio of carbon, hydrogen, and oxygen, but the molecular formula shows how many atoms are actually present in the molecule.
How it works
Four short steps
Start with the empirical formula
Enter the simplest whole-number formula.
Calculate the empirical formula mass
Add up the atomic masses of the empirical formula.
Divide molar mass by empirical formula mass
This gives the whole-number multiplier n.
Multiply every subscript by n
The result is the molecular formula.
Molecular formula from empirical formula
n = Molar Mass ÷ Empirical Formula Mass
Molecular Formula = Empirical Formula × n
The multiplier should be a positive whole number.
You need the compound's molar mass to determine the molecular formula from its empirical formula.
Keep going
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FAQ
Frequently asked questions
What is a molecular formula?
It shows the actual number of atoms of each element in a molecule.
How do I calculate a molecular formula from an empirical formula?
Calculate the empirical formula mass, divide the compound's molar mass by it, and multiply every empirical-formula subscript by the resulting whole-number multiplier.
What is the difference between an empirical and molecular formula?
The empirical formula gives the simplest whole-number ratio. The molecular formula gives the actual number of atoms in the molecule.
Can the molecular formula be the same as the empirical formula?
Yes. If the multiplier is 1, the empirical and molecular formulas are the same.
What if the multiplier is not a whole number?
Check the empirical formula and molar mass. A valid molecular formula should be a whole-number multiple of the empirical formula.
Can I find a molecular formula without molar mass?
No. The empirical formula gives the ratio of atoms, but the molar mass is needed to determine the actual multiple.