BTU Calculator

A British Thermal Unit (BTU) is a measure of heat output from a radiator. Depending on the size of your room, the number and type of windows and what the room is used for, you'll need more or less heat. If you have a higher BTU requirement, it might be better to use more than one radiator to deliver the heat you'll need to a room. The total BTU output of several smaller radiators may meet your needs.






Room Type?


Does the room have?

 French Windows 
  North Facing Walls 
  Double Glazing 
 Required BTUWatts

This calculator will give an approximate value of the BTU/Watts required for your room. Consider other factors such as if the room has large windows or more than one outside walls.


If you're measuring your room in metres then measure to the nearest centimetre. Enter your measurments using decimal notation for example 425cm would be entered as 4.25m.

When it comes to measuring the height if you have a vaulted or sloping ceiling use an average.


For example a room measuring 4 x 3 x 2.5 metres simply enter the measurements then set the room type. Tick the relavent boxes for French windows, North facing walls or double glazing. Then click the submit button.

So if our room was a bedroom measuring 4 x 3 x 2.5 metres and has double galzing then this gives results of 3811 BTU and 1117 Watts.


Please call us on 01663 749027 for advice.