Trevor, I am not Norma, but the BS thermometer measures the temp in the space above the top stone. We normally use IR thermometers to measure the temp of the bottom stone. So there is no simple conversion or even relation between the two. I suggest you look for a cheap IR, I have been using my BS for years, and still use the IR before most launches- the temp of the bottom stone is pretty important in whether the bottom will be pale or charred when the top is done, and there is no way to tell without an IR thermometer. You don't need anything very precise, it just has to be repeatable so that you know when the gun reads x, it is time to load the pie.