BTU Calculator


You will need 51,408 BTU/hour or 15,066 watt.

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Room/House Width
Room/House Length
Ceiling Height
Insulation Condition
Temperature to Increase
or Decrease

Depending on your local winter/summer temperature,
e.g. 75F for Boston winter, 35F for Atlanta winter.


The British Thermal Unit, or BTU, is an energy unit. It is approximately the energy needed to heat one pound of water for 1 Fahrenheit. 1 BTU = 1,055 joules. 1BTU/hour = 0.293 watt.


  • One very well-insulated 1,000-square-foot home in Boston needs around 24,000 BTUs to heat in winter.

  • One 2,000-square-foot-home with normal insulation conditions in Washington, D.C., needs a 48,000 BTU air conditioner for adequate cooling in summer.