INSIGHTS HUB > Homeowner > The definitive guide to standard UK window sizes

The definitive guide to standard UK window sizes

January 3, 2023

When on the lookout for new windows, size isn’t necessarily the headline feature for a lot of people.

Type of material, style, glazing options, level of security, colours; all these factors are probably higher up on a list of considerations than dimensions.

That doesn’t mean window size should be glossed over during the buying process though, not in the slightest. 

If you’re having your windows replaced, it’s vital you have the correct measurements before you go window shopping, otherwise installation will, in all likelihood, prove problematic. 

While many homeowners now go down the bespoke made-to-measure route, standard UK window sizes are still common across the country. 

Knowing the different window types, and their standard size, can therefore make buying and installing a whole lot simpler. 

Average UK Windows Sizes By Type 

With so many different windows available, it’s vital you have as much information in front of you as possible so you’re able to make an informed decision. 

The handy table below provides a snapshot of standard UK window sizes for a variety of styles. 

Window typeWidth (in)Height (in)
Casement23, 25, 2935, 47, 53
Flushsash23, 25, 2935, 47, 53
Reversible23, 5535, 55
Tilt and Turn31, 47, 5531,47, 55
Twinsash23, 25, 2935, 47, 53
Bay41, 12435, 77
Vertical Slider2436

Average window size by room type 

Bedroom:  24×36, 36×48, 34×62

Bathroom: 18×24, 24×24, 24×36 

Kitchen: 21×45, 25×35, 29×59

Living room: 48×48, 60×48, 72×48

How do I know the size of my windows?

The size chart we have posted here is intended to be a guide.

As we mentioned earlier, more people nowadays are opting for bespoke window solutions, so shapes and sizes can vary quite drastically.

If you are replacing your windows, it is essential you get the right measurements, and so we would always recommend contacting a professional installer to ensure this process is carried out properly.