Abstract: Xylene is used as a solvent in various industrial fields and is a flammable substance its Lower Flammability Limit (LFL) and stoichiometric ratio are crucial factors for safety in relation to fire which is a major risk. Although, many related studies on the LFL and stoichiometric ratio of xylene have been conducted to date, the results from these studies are inconsistent. Consequently, data from previous studies are confusing to industries that use xylene in various processes. This study aimed to investigate the exact correlation between the LFL and the stoichiometric ratio of xylene. To determine this correlation, flash points were measured using a tag closed cup apparatus (ASTM D56-15) and a new and improved formula was derived for the relationship between the LFL and the stoichiometric ratio of xylene through the measured flash points. This study provides important basic safety data for industrial fields that use xylene a flammable substance.