Flue Gas Nitrogen Calculator

Completing the Dry Flue Gas Composition Picture

Nitrogen makes up the large majority of dry flue gas by volume, since it passes through combustion essentially unreacted. Rather than measuring it directly, it's normally found by subtracting the other measured components from 100%.

The Formula

N2% = 100 − O2% − CO2%

Worked Example

Flue gas measuring 2.7% O2 and 10.2% CO2:

N2% = 100 − 2.7 − 10.2 = 87.1%

How to Use This Calculator

Enter the measured Oxygen percentage.
Enter the measured CO2 percentage.
Select Calculate to get nitrogen percentage by difference.

Related Calculations

Need O2 or CO2 estimated from excess air instead of measured directly? See the Flue Gas Oxygen Calculator or the Flue Gas CO2 Calculator.