Propane and natural gas burn at nearly equal flame temperatures (3,560 degrees Fahrenheit). However, propane yields more energy per unit volume than natural gas does. For many years it was a commonly held belief that propane burned hotter than natural gas, but that was due to a miscalculation in the volume needed to create equal yields.
In order to create the same yield in heat, the volume of natural gas used must be about 2.5 times that of propane. Burning one cubic foot, natural gas will yield about 1,012 BTU's of heat, while propane yields 2,520 BTU's of heat in that same cubic foot.
The automatic ignition temperature, which is the minimum required temperature to ignite gas or vapors in the air without the presence of a spark or flame, varies slightly between natural gas and propane. The automatic ignition temperature for methane, or natural gas, is 1076 degrees Fahrenheit. Propane requires a slightly lower automatic ignition temperature of 842 degrees Fahrenheit.