Molecular Formula Calculator
Determine the molecular formula from the empirical formula and measured molar mass.
About Molecular Formula Calculator
The molecular formula is always a whole-number multiple of the empirical formula. Glucose has an empirical mass of 30.03 and a molar mass of 180.16, giving a multiplier of six and the formula C₆H₁₂O₆. A multiplier that is not close to a whole number signals an error in either the composition data or the molar mass determination.
Formula
Molecular Formula
Multiplier = molar mass ÷ empirical formula mass, rounded to the nearest whole number
- multiplier
- How many empirical units make up one molecule
Worked example
With the default values below, Molecular Formula Calculator returns Formula Multiplier of 6.0000. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Empirical formula massminimum 0 g/mol
- 30.026 g/mol
- Measured molar massminimum 0 g/mol
- 180.156 g/mol
Results
- Formula Multiplier
- 6.0000
- Nearest Whole Multiplier
- 6
- Molar Mass From the Whole Multiplier
- 180.1560 g/mol
- Discrepancy Against the Measured Mass
- 0.0000%
- Verdict
- Consistent — the whole-number multiplier fits the measured mass
Step by step
- 1Values used
- 2Molecular Formula
- 3Formula Multiplier= 6.0000
- 4Nearest Whole Multiplier= 6
- 5Molar Mass From the Whole Multiplier= 180.1560 g/mol
- 6Discrepancy Against the Measured Mass= 0.0000
- 7Verdict= Consistent — the whole-number multiplier fits the measured mass
Assumptions and limits
- The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Molecular Formula calculated?
Multiplier = molar mass ÷ empirical formula mass, rounded to the nearest whole number The molecular formula is always a whole-number multiple of the empirical formula. Glucose has an empirical mass of 30.03 and a molar mass of 180.16, giving a multiplier of six and the formula C₆H₁₂O₆.
Why does Molecular Formula matter?
A multiplier that is not close to a whole number signals an error in either the composition data or the molar mass determination.
What values do I need to enter?
This calculator takes 2 inputs: Empirical formula mass, Measured molar mass. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.