Calculates Heat Output Required in Watts and BTU’s


This room heating calculator will help calculate the required heat output (in BTU’s and Watts) when purchasing / upgrading central heating or electric heating systems. You can use this calculator to help choose from our selection of electric panel heaters, heated towel rails and designer radiators, available to buy from this website.

Enter Room Sizes

Room Height (m)
Room Width (m)
Room Length (m)
Room Type
North Facing?
Room has French / External Doors?





What is a BTU?

The British Thermal Unit (BTU) is a measurement of heat output, commonly from a central heating radiator or heated towel rail. The BTU output that you will require is dependant on factors such as the size of your room, the number and type of windows and what the room is used for.

If your room is quite large, and you have a high BTU requirement, you may wish to consider several radiators to meet the heating requirement of the room.

How do I choose the right panel heater / heated towel rail / designer radiator?

The BTU or Watt value of all our heating products is listed in the product descriptions, helping you select the products that meet your requirements. Our heated towel rails and designer radiators are listed in BTU’s. Our electric heaters (panel heaters, oil filled electric radiators) are listed in Watts.