Empirical and Molecular Formula Calculator
Fit a small whole-number empirical formula to entered element masses or mass percentages, with an optional molecular mass.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Divide each element mass by its stored atomic weight. Normalize mole amounts by the smallest positive amount. Try small integer multipliers and reduce their common divisor. Compare an optional molecular mass with an integer formula multiple.
Mole ratio=(element mass/atomic weight)/smallest mole amount
Worked example
Mass percentages near C 40.0, H 6.71 and O 53.29 fit CH2O; a molecular mass near 180.156 g/mol gives C6H12O6.
Assumptions and input details
Use one common mass basis and unique supported element symbols. Multipliers through twelve and empirical counts through one thousand are tested. A tolerance fit is not a unique chemical identification. Molecular-mass agreement must be within one percent.
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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Compare a measurement with a reference or calculate symmetric percentage difference between two values.
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