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BTU Calculator

Our BTU calculator will help you work out the heat requirement for your room, and recommend the number of radiators you will need to heat it.

BTU Calculator

How is the required amount of BTUs to heat a room calculated?

First you need to calculate the cubic volume of your room (in feet or metres) by multiplying the height, width, and length of the room (done for you with our free calculator). We then apply further mathematical equations to determine the heat loss in your room (whether that is through the floor, walls, windows, ceiling, or roof) before delivering, what we consider to be, the most accurate guide when selecting a radiator or heated towel rail to heat your room efficiently; this means to a comfortable temperature at the lowest possible fuel costs to you.

What if the radiator I want doesn’t precisely match my BTU score?

Don’t worry about it;

  • a radiator with a grossly insufficient BTU output will never heat a room efficiently,
  • a radiator with a much higher BTU output than required will overheat a room

Radiator Renovator recommends that you go no lower than 10% below the recommended BTU output, with radiators that have a much higher BTU output than necessary we supply a lovely range of valves which means that you can turn your cast iron radiator down.

Please remember, it is also possible to combine radiators to achieve a BTU level. Many rooms have more than one radiator in them for this very reason.

What is a BTU?

A British Thermal Unit (BTU) is a measure of heat output from a radiator. We normally measure how many BTU’s your room requires to heat it properly. This will depend on the size of your room and what it is used for. Once we know how many BTU’s your room needs we can achieve this by providing one large radiator or any number of smaller radiators depending on your own preference.

How do I choose the right radiator?

We can help you choose the most suitable radiator(s) for you. There are many designs and sizes of radiators to choose from; we will work alongside you so you can get it just right.

BTU calculator
IF BTU output is too high turn the radiator down.