BTU Calc

Use this calculator to estimate the cooling needs of a typical room or house, such as finding out the power of a window air conditioner needed for an apartment room or the central air conditioner for an entire house.

What is a BTU?

The British Thermal Unit, or BTU, is an energy unit. It is approximately the energy needed to heat one pound of water by 1 degree Fahrenheit. 1 BTU = 1,055 joules, 252 calories, 0.293 watt-hours or the energy released by burning one match. 1 watt is approximately 3.412 BTU per hour.

BTU is often used as a point of reference for comparing different fuels. Even though they're physical commodities and quantified accordingly, such as by volume or barrels, they can be converted to BTUs depending on the energy or heat content inherent in each quantity. BTU as a unit of measurement is more useful than physical quantity because of fuel's intrinsic value as an energy source. This allows many different commodities with intrinsic energy properties to be compared and contrasted; for instance, one of the most popular is natural gas to oil.

BTU can also be used pragmatically as a point of reference for the amount of heat that an appliance generates; the higher the BTU rating of an appliance, the greater the heating capacity. As for air conditioning in homes, even though ACs are meant to cool homes, BTUs on the technical label refer to how much heat the air conditioner can remove from their respective surrounding air.