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How To Measure Your Radiator

If you are replacing your radiator with a similar model, you are replacing it like for like. So that you can install your radiator smoothly, it’s important to take down the right measurements to avoid complications later on. By documenting the details in millimetres, you’ll be able to match the measurements in-store or online.

Make sure you have the right tools to hand as this will make the job much easier. You’ll need a tape measure, and either a pen and notepad to record the measurements - or you can use your phone to do this. The four key measurements you’ll need to make a note of are the radiator height, its width, and two pipe measurements. We’ll explain.

  1. For the radiator’s height, measure from the lowest point of your radiator to the highest.

  2. For the radiator’s width, measure from the furthest point on the left to the furthest point to the right of your radiator.

  3. You’ll also need to measure the left pipe centre to the right pipe centre - that’s the distance between the two pipe inlets that feed into, and out of, your radiator.

  4. Lastly, you’ll need to measure the wall surface to the pipes’ centres. This is a useful measurement if you aren’t altering any plumbing as part of the radiator replacement process. Begin at the wall and measure the short gap between the wall to the centre of the pipes.

Two extra measurements that can also be useful are the depth of your current radiator. If it sticks out, you might consider replacing it with a slimline version. A final measurement is one that will determine how much space is behind your radiator. To do this, simply measure the distance between the wall and the radiator.

Don’t forget to take all your measurements in millimeters!

What Size Radiator Do I Need?

You might be asking yourself what size is a standard radiator? Or perhaps, are UK radiators standard sizes? The answer that radiators do not come in a single standard size. Radiators traditionally were made to standard sizes. In recent years, radiators have been given a makeover. Now they come in different sizes and shapes that not only look modern, but are also designed with excellent heat output.

You may also want to know how to correctly size my radiator for a room? In the UK, radiator efficiency is calculated in British Thermal Units (or BTU). This calculation is the ideal radiator to room size ratio needed for your radiator to sufficiently heat the room. The sum takes into account the size and the type of room - meaning what it’s used for - whether a kitchen, dining room or bedroom. With this information, you can even work out the BTU for your whole house! This is helpful when it comes to buying a new boiler.

The table below can help you estimate the correct BTU to correctly heat the rooms in your home.


Multiplication Factor

Lounge and Dinning Room

Multiply cubic feet by 5


Multiple cubic feet by 4

​Common areas - e.g. hallway

Multiple cubic feet by 3

For double glazing

Deduct 10%

Radiator Tips

Whether buying in person or online, in most cases, you’ll need to match the measurements of the new radiator precisely with the old one. However, there are instances where you will need to adjust your plumbing to suit the new dimensions. An example of this is if you are making changes to your bathroom and are going for a completely different look. Or perhaps you want your radiator to do something other than simply heat a room - such as installing a heated rail.

Now you’re ready to look for a new radiator. It’s a good idea to do some research online, then visit a showroom so that you can see the radiator on display to appreciate the radiator sizing as it might appear in your home. Then it’s time to shop around online for the best deal.

Does My Radiator Need Replacing?

Keeping radiators around your home in good condition and working as they are intended not only helps you save money on your heating bills, but an energy-efficient home is also better for the environment. Radiators can be subject to common problems from time to time. By looking after your radiators, you’ll ensure they continue to work as effectively and efficiently as possible.

For instance, did you know that bleeding a radiator is a quick and easy job and one that should be done regularly? You might like to know how to go about bleeding a radiator. Check out our handy guide with step by step instructions on how to do this.

Balancing your radiator is another important - yet simple maintenance job.

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