Ignitability tests were completed on three materials using the ISO ignitability apparatus and the Cone Calorimeter. A large number of replicate tests were made at each heat flux level to obtain reliable standard deviation values for the results. The possible errors in results were minimized using the very same external conditions. Both methods can be used to measure ignitability, although there is some systematic difference in the measured ignition times. The ISO ignitability tests give slightly shorter ignition times caused by difference in convective heat flow. These results show, however that it is possible to find a simple relation between the results of the two test methods.