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Empirical Formula Calculator

Determine the empirical formula of a compound based on elemental percentage composition.

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Calculation Parameters

Specify your stoichiometry inputs.

Carbon (%)

0%100%

Hydrogen (%)

0%100%

Oxygen (%)

0%100%

Calculated Result

Empirical Formula

CH₂O

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Expert Tip

Ensure units are correctly formatted (e.g. Kelvin for gas temperatures and liters for volumes) to get chemically accurate outputs.

How this Calculator Works

This calculator determines the empirical formula of a compound based on the mass or percentage composition of its constituent elements. Adjust the parameters using the sliders below:

Element 1 % (e.g., C): Mass percentage of the first element (Default: 40.0)
Element 2 % (e.g., H): Mass percentage of the second element (Default: 6.7)
Element 3 % (e.g., O): Mass percentage of the third element (Default: 53.3)

The results are computed instantly and updated in the results panel on the right.

Formula & Methodology

Moles of Element_i = Mass % of Element_i / Atomic Mass_i Relative Ratio = Moles of Element_i / Smallest Mole Value Empirical Formula = Ratios converted to lowest whole numbers

Where:

Mass %: Percent composition of each element by weight.
Atomic Mass: Standard atomic weight (e.g., C ≈ 12.011, H ≈ 1.008, O ≈ 15.999 g/mol).

Step-by-Step Calculation Example

To calculate the empirical formula for a compound with 40.0% C, 6.7% H, and 53.3% O manually, follow these steps:

Identify the input parameters. For example:
- C = 40.0%, H = 6.7%, O = 53.3%
Apply the formula:
Moles calculation: - Moles of C = 40.0 / 12.011 = 3.33 mol - Moles of H = 6.7 / 1.008 = 6.65 mol - Moles of O = 53.3 / 15.999 = 3.33 mol Divide by smallest value (3.33): - C Ratio = 3.33 / 3.33 = 1 - H Ratio = 6.65 / 3.33 ≈ 2 - O Ratio = 3.33 / 3.33 = 1 Result Formula: CH₂O
Verify the calculated value which is updated instantly in the results panel on the right.