The British Thermal Unit(BTU) is an energy unit approximately equivalent to the energy needed to heat one pound of water by 1 degree Fahrenheit. 1 BTU = 1,055 joules, 252 calories, 0.293 watt-hour. This BTU calculator helps in estimating the amount of heat produced in the room given the required values. The british thermal unit calculator estimates the amount of BTUs required to heat or cool homes based on the dimensions, insulation conditions, and the desired temperature changes.