Flash points (T-FP) of organic compounds are calculated from their flash point numbers, N-FP, with the relationship T-FP = 23.369N(FP)(2/3) + 20.010N(FP)(1/3) + 31.901. In turn, the N-FP values can be predicted from boiling point numbers (Y-BP) and functional group counts with the equation N-FP = 0.974Y(BP) + Sigma(i)n(i)G(i) + 0.095 where G(i) is a functional group-specific contribution to the value of N-FP and n(i) is the number of such functional groups in the structure. For a data set consisting of 1000 diverse organic compounds, the average absolute deviation between reported and predicted flash points was less than 2.5 K.