What are BTUs? How to calculate them?

BTU explanation

What is BTU?

BTUs, or British Thermal Units, are a unit of measurement for heat energy. One BTU represents the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. BTUs are commonly used to measure the cooling or heating capacity of appliances such as air conditioners, heaters, and space heaters. The higher the BTU rating, the more heat or cooling the appliance can produce.

How do I calculate the required BTUs?

Calculating BTUs requires taking into account several factors, including the size of the room to be heated or cooled, insulation, sun exposure, number of occupants, number of windows, etc. Here is a basic formula for estimating the BTUs needed to heat or cool a room:


For heating:

  1. Calculate the area of ​​the room in square feet.
  2. Multiply this area by 15 if the room is well insulated, or by 20 if it is less well insulated.
  3. Add 1,000 BTU per occupant of the room.

For cooling:

  1. Calculate the area of ​​the room in square feet.
  2. Multiply this area by 10.
  3. Add 400 BTU per occupant of the room.

These formulas provide a general estimate of the BTUs needed.

An automatic BTU calculator is available on our website www.kanartic.ca. Feel free to use it!

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