What is an empirical formula?

An empirical formula is the simplest whole-number ratio of atoms in a compound. For example, glucose (C6H12O6) has the empirical formula CH2O because all subscripts reduce by a factor of 6.

Can I enter masses instead of percentages?

Yes. If you have actual masses in grams, enter them directly — the math is identical since percentages are just masses out of 100 g. Toggle the input mode using the button above the element rows.

What if my percentages do not add up to 100%?

The calculator still works correctly because it divides by the smallest mole value rather than relying on the sum. Small rounding errors (up to a few percent) are handled automatically.

How does the calculator handle ratios like 1.5 or 2.33?

It multiplies all ratios by the smallest integer (up to 6) that converts every value to a whole number. A ratio of 1.5 becomes 3:2 when multiplied by 2.

Is there a limit on the number of elements?

You can add up to 10 elements, which covers virtually all common compounds including complex organic molecules.

Where do the atomic masses come from?

The tool uses IUPAC standard atomic weights rounded to four significant figures for the most common elements in chemistry.

Empirical Formula Calculator

Name: Empirical Formula Calculator
Availability: InStock
Author: Nham Vu

Enter element symbols and their percentages or masses to instantly calculate the empirical formula of a compound.

Elements

Input:

Quick Examples

Enter elements and click Calculate

Empirical Formula

Simplest whole-number atom ratio

Calculation Steps

Element	Mass (g)	At. Mass	Moles	Ratio	Integer

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Summary

Enter element symbols and their percentages or masses to instantly calculate the empirical formula of a compound.

How it works

Enter each element symbol (e.g., C, H, O, N) and its percentage composition or mass.
The calculator divides each mass by the element's atomic mass to get moles.
All mole values are divided by the smallest to give a mole ratio.
Ratios are multiplied by a common factor (1–6) until all become whole numbers.
The resulting integers form the subscripts of the empirical formula.

Use cases

Determine the empirical formula from combustion analysis data.
Convert percent composition results from lab experiments.
Verify molecular formulas by comparing to the empirical formula.
Solve general chemistry homework and exam problems.
Check formula derivations for organic and inorganic compounds.
Cross-check results from spectroscopy or elemental analysis.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu