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BTU Radiator Heat Output Calculator

What are BTUs?

BTUs are ‘British Thermal Units’, the unit in which radiator efficiency is measured. Factors such as room dimensions, window size and wall material are used to calculate the required outputs of radiators, in order to adequately heat a room.

How do I Calculate the BTUs for my Room?

The best way to get an accurate calculation is to enlist the services of a plumber. However, Best Heating's BTU Calculator is an accurate guide as to what level of BTU and Watt output will efficiently heat your room. Please note: the calculated figure is for the combined heat output of all radiators and/or towel rails in your room (larger rooms may require more than one).

Room Dimensions
Width * Height * Length *
Window Area X²: *
Room Information
Type of room: *
What is below the room? *
What is above the room? *
Select type of outside wall: *
Select type of window: *
Select number of outside walls: *


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