Standard Window Sizes: Average window sizes in the UK

25 March 2021
Updated 4 January 2024

Thinking of replacing the windows in your home but not sure what size windows you need (or want)? Measuring up for new windows isn’t everyone’s cup of tea. But we’re here to help guide on along the right path, by looking at what the standard window sizes in the UK are.

Whilst there are some common window sizes in the UK, it is important to bear in mind that many homeowners opt for a more bespoke size, allowing them to customise their home as they see fit.

We will take a look at common uPVC window sizes used for uPVC windows, though these are generally shared with other window materials as well, including aluminium and timber windows.

What are the standard window sizes in the UK?

uPVC windows come in all sorts of shapes and sizes.

If you’re thinking of replacing your existing windows, it’s recommended that your replacement windows are the same size as the existing windows, unless of course, you’re trying to achieve a specific benefit.

Let’s take a look. We will start with the largest sizes and work our way down.

Average window heights

Common uPVC window heights in the UK include:

Millimetres (mm)Inches (in)

Average window widths

Common uPVC window widths in the UK include:

Millimetres (mm)Inches (in)

Don’t be put off if you want something larger or smaller. Window sizes can vary from property-to-property, and whilst the window sizes we have listed are some of the more common sizes found in the UK, they are by no means your limits.

Many window installers will offer a made to measure option, where they will come out and measure the size of window that you’re looking to have fitted, and then will have that exact size manufactured.

Should I choose larger or smaller windows?

The size of window you choose can depend on many factors, including where the window will be placed in the property, and how much natural light you would like in your home.

Generally speaking, bathrooms and kitchens tend to have smaller windows, whereas larger windows will be placed at the front and back of the house, usually in the living room and conservatory.


Are you finding that some rooms are a little dark during the day? If that’s the case, a larger window might beneficial, as more natural light will be able to enter the room. This could inadvertently save a little bit on energy bills, as you’re not having to keep the lights on for as long during the Summer days.

Design your windows online

Did you know that it is possible to enter the window sizes that you want online and design your windows, all from the comfort of your home?

From entering the sizes, to picking the colour of the window frames, and adding accessories, our online window design tool will let you see how your window will look, and then receive a quote from 3 local companies.

Not looking for a window installation service? Take a look at uPVC windows supply only if you’re into DIY or in the trade.