Radiator Size Calculator

Using our radiator size calculator will help you decide what dimensions your new radiator should be to accommodate your space and how to calculate the radiator size for your room. Using our radiator sizing guide is great for physical measurements, but another useful tool to help you calculate how much heat output is appropriate for your room is our BTU Calculator. This heat loss calculator will work alongside our radiator size calculator for UK radiators, helping create a radiator size chart that will direct you to which model of radiator is most suitable for your room.

The size of radiator you need for your room will be dependent on its dimensions. If you are replacing an existing radiator, for example, and are wondering how to calculate radiator size for a room, follow these 4 simple steps:

• Measure the height of where the radiator will be placed.
• Measure how wide you need your radiator to be.
• Measure the pipe centres (from the centre of the left-hand pipe inlet to the centre of the right)
• Measure the wall-to-pipe centres (from the centre of the pipe inlet to the wall)

You can then use our radiator size calculator to input the measurements to see which of our ranges will be suitable as a replacement.

Radiator sizes are not consistent over different models, due to their varying dimensions. For example, a Vertical Radiator will be much taller than it is wide when compared to a standard horizontal radiator. Using our radiator size tool and BTU calculator can ensure you choose the right dimensions for your room, rather than choosing the same size for every room which may not be as energy efficient.

We have a range of radiator sizes at Stelrad that are suitable for many different room requirements. For example, our Classic Compact radiators range in height between 300mm – 700mm and widths of 400mm – 2400 mm, whereas our Compact Vertical is 1800mm in height with a choice of widths between 400mm – 600mm.

As you will find when browsing our range, “Standard” doesn’t mean one-size at Stelrad. We have many options because every room is different and every property is differently sized, helping you choose the right size for your needs. You’ll see full details of the available sizes to suit your needs by using our radiator size calculator.

British Thermal Unit (BTU) is the traditional unit of heat to measure the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. As this can be quite complex, using a BTU calculator makes working this out easy. Put simply, the higher the BTU output of a radiator, the more heat it can produce. The size, shape, and material used for the radiator will all determine its BTU output.

To know the number of BTUs required per radiator, this will depend on the number of radiators in the room. Divide the total BTU requirement by the number of radiators. This will calculate the average BTUs required for each radiator. You can use our BTU calculator to follow a step-by-step guide to calculate heat loss in your home for any room. This will help you choose the right size radiator with your taken room measurements, as well as details about the walls, floor, glazing etc. it has.