Hydrodesulfurization of cracked gasoline is now a vital step for the production of clean fuels. Along with sulfur removal, however, olefin saturation occurs. Knowing the olefin content of the gasoline is key to achieving a proper design, as olefin saturation largely sets the heat release and hydrogen consumption that will be experienced. More specifically, the molar concentration of the olefins must be known, and determining this in cracked gasoline is not as straightforward as it seems. There are a number of seemingly appropriate analytical methods for olefin measurement. This study examines several of the more common methods used in the refining industry and compares their performance on a sample of full-range FCC gasoline. A case is made that the bromine number is the most appropriate measurement to use as the basis for a reactor design.