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BTU Calculator

Please type your room dimensions below

Type of Room:
Additional Factors:
Required Watts:

These figures are a guideline base only

What is BTU?

British Thermal Units (BTU) measure heat output from radiators. Some rooms will need more heat, and others less; it depends on the size of the room, its function, and the number & type of windows in the room.

When purchasing a radiator from Designer Radiators Direct, it's best to measure the BTU of your room so you can find the most appropriate radiator for it. Larger rooms are likely to require a greater number of radiators. Use our BTU calculator to find out what BTU and Watt output will efficiently heat your room.

How is BTU measured?

A plumber can get you the most accurate BTU calculation, but our BTU calculator is also very accurate.

Please note that the calculated BTU figure is the combination of all heat output in your room. This includes radiators and heated towel rails. Larger rooms, such as Living Rooms, may require several radiators spread evenly across the room. If this is the case, you should divide the calculated BTU between the number of radiators you need.