BTU Heat Output Calculator

The BTU (British Thermal Unit) calculator can be used to work out how much radiator power you need.  Numerous factors can affect this, such as types of window and room dimensions. Feel free to use our BTU calculator below.

Use this calculator to determine the required heat output to heat your room.

A BTU (British Thermal Unit) is a unit of measurement of heat per hour. The BTU calculator will determine the size and quantity of radiators needed per room.

Room Type

Room Dimension

Extras (select all that apply)

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