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BTU Calculator

Estimate the air-conditioner or heater capacity (in BTU) a room needs.

How it works Report a problem


BTU Calculator

Calculate the thermal energy required to heat or cool your room.

About the BTU Calculator

Estimate the air-conditioner or heater capacity (in BTU) a room needs.

How to use the BTU Calculator

  1. Enter the room Length, Width and Height in feet.
  2. Set the Insulation Quality, Sun Exposure, Number of Occupants and whether it is a kitchen.
  3. Press Calculate BTU.

Formula and method

A common rule of thumb is about 20 BTU per square foot, adjusted for sun, insulation, occupants and heat sources such as kitchens.

Tips

  • An oversized unit cycles on and off and cools poorly. An undersized one runs constantly.

Frequently asked questions

What does BTU stand for?
British Thermal Unit, a measure of heat energy.