Empirical Formula Calculator

The Empirical Formula Calculator finds the simplest whole-number ratio of elements in a chemical compound — the foundational step in identifying an unknown substance from lab data. Select your calculation mode (mass percentage or grams), then enter each element symbol and its corresponding value for up to four elements. The calculator returns the empirical formula, total percentage, and an optional step-by-step breakdown of the mole ratio reduction.

Calculation Mode *

Enter chemical symbol (C, H, O, etc.)

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Results

Empirical Formula

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Total Percentage

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Calculation Status

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Results Table

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Frequently Asked Questions

What is an empirical formula?

An empirical formula represents the simplest whole-number ratio of atoms in a compound. It shows the relative number of atoms of each element present, but not the actual number of atoms.

How is empirical formula different from molecular formula?

The empirical formula shows the simplest ratio of atoms, while the molecular formula shows the actual number of atoms in a molecule. For example, glucose has molecular formula C₆H₁₂O₆ but empirical formula CH₂O.

What is the empirical formula of ethanol?

Ethanol (C₂H₆O) has the empirical formula C₂H₆O, which is already in its simplest form since the ratio 2:6:1 cannot be reduced further while maintaining whole numbers.

Can a compound have multiple empirical formulas?

No, a compound can have only one empirical formula. However, multiple compounds can share the same empirical formula but have different molecular formulas.

What if my percentages don't add up to 100%?

Ideally, mass percentages should total 100%. Small deviations (±2%) are acceptable due to experimental error, but larger differences may indicate missing elements or measurement errors.

How do I convert from grams to percentage?

To convert mass in grams to percentage, divide each element's mass by the total mass of the sample, then multiply by 100. For example, if you have 12g C and 4g H in a 16g sample: C = (12/16)×100 = 75%, H = (4/16)×100 = 25%.