Empirical Formula Finder

Determine the empirical formula of a compound from elemental percent composition. Supports C, H, O, and N.

Carbon (%)

Hydrogen (%)

Oxygen (%)

Nitrogen (%)

Tab to move between fields

Empirical Formula

CH2O

Empirical Formula Weight30.03 g/mol

C Mole Ratio1

H Mole Ratio1.999

O Mole Ratio1

N Mole Ratio0

Total Composition100 %

How to Use This Calculator

Enter the percentage composition for carbon, hydrogen, oxygen, and nitrogen.
Percentages must sum to 100% (or close to it with rounding).
Review the Empirical Formula string and Empirical Formula Weight (g/mol).
Divide the molecular weight by empirical weight to find the molecular formula multiplier.

What each input means

Carbon (%): Mass percent of carbon from combustion analysis or elemental analysis
Hydrogen (%): Mass percent of hydrogen
Oxygen (%): Mass percent of oxygen (often found by difference: 100% minus other elements)
Nitrogen (%): Mass percent of nitrogen — set to 0 if the compound contains no nitrogen

Moles = %element / atomic weight; Ratio = moles / smallest moles

Identify Input Parameters
4 parameters
Carbon (%) = 40, Hydrogen (%) = 6.71, Oxygen (%) = 53.29, Nitrogen (%) = 0 = 4 input(s) provided
Calculate Empirical Formula
CH2O = CH2O
Calculate Empirical Formula Weight
Empirical Formula Weight
30.03 = 30.03
Calculate C Mole Ratio
C Mole Ratio
1 = 1

Engine last updated July 21, 2026. Checked against 1 independently-derived test — how we verify calculators.

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