The fire calorimeter is used by encasing a small sample in aluminum foil, wool, and a retainer frame that is ignited below an exhaust hood. A conical heater is placed in between in order for materials to combust. The cone-shaped inconel heating element provides a controllable radiant flux onto the sample, turning electricity into heat not unlike an electric toaster or oven. The flammability of a sample can be characterized as a function of heat flux onto a sample. The conical heater is open in its center, allowing products of combustion to flow upwards into an exhaust duct.