Flue Gas SO2 Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 27, 2026Where SO2 emissions come from
Sulfur present in fuel combines completely with oxygen during combustion to form sulfur dioxide - since this reaction follows fixed stoichiometry, SO2 output can be calculated directly from a fuel's known sulfur content before any downstream flue gas desulfurization.
Worked example
For 1,000 kg of fuel containing 2% sulfur by mass:
Sulfur Mass = 1000 x 2% = 20 kg
SO2 Mass = 20 x 2 = 40.0 kg SO2
The factor of 2 comes directly from molecular weights: sulfur dioxide (SO2, molar mass 64) contains one sulfur atom (molar mass 32) plus two oxygen atoms, so every kilogram of sulfur burned produces exactly twice its own mass in SO2.
This calculation estimates uncontrolled SO2 output - actual emissions to atmosphere depend heavily on whether flue gas desulfurization equipment (scrubbers) is in place downstream.