Summary This work aims to explore possible ways of improving the precision of ignition measurements in the cone calorimeter. Both inherent repeatability of parts of the testing equipment and operator-dependent variations are considered. Inherent repeatability is indicated to be slightly improved if the test samples used are circular rather than square. Operator-dependent variation is discussed in terms of the method used for determining ignition. Four procedures are compared, namely, visual observation, usage of a light sensor, and looking at the peak of the second and first derivatives of the mass loss and heat release curves, respectively. Results indicate that the preferable operator-independent method depends on the test conditions; the derivative of the heat release rate is an alternative to the mass loss rate derivative when the scale is of standardised quality. A light sensor for ignition time observation is a good option when the surrounding light is not changed during the test.