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How much does a kitchen extension cost?

9 min read
Feb '26 • by Heather

Quick summary

A kitchen extension costs between £40,000 and £200,000 depending on size, location, and type. For a 30 sqm extension, building costs from a small company range from about £54,600 to £97,500 outside London, and £63,600 to £90,000 in London. Larger or more complex projects can go higher, especially with premium materials or design.

Often referred to as the heart of the home, it’s no wonder kitchen extensions are one of our most commonly received requests. Not only do they open up a much used space, but a kitchen extension is a great way of adding value to any property. Depending on the size of the project, and your location, a kitchen extension cost can vary anywhere between £40K to £200K.

Now, you’re probably wondering why there’s such a wide price range. As with any home extension, there are plenty of factors that will affect your budget, including: location, extension type, size, complexity, materials, plus much more.

To help you get your budgeting spreadsheets in order, here’s what you’ll need to consider when trying to work out how much a kitchen extension costs.

How much does a kitchen extension cost to build?

The construction stage is where most (but not all) of your budget will be spent. Therefore, it’s useful to get to grips with these costs off the bat. The three defining factors for this stage of your project are: size and quality of your chosen contractor, the type of kitchen extension being constructed, and whether or not you live in or outside of London.

Here are rough estimates of how much it costs to build a variety of kitchen extensions.

Calculate the cost of your kitchen extension build.

Side return kitchen extension cost

Contractor London Estimate (Ex. VAT) Outside London Estimate (Ex. VAT)
Low end High end Low end High end
Individual £52,000 £75,000 £43,313 £61,875
Small Company £63,600 £90,000 £51,975 £74,250
Large Company £68,250 £97,500 £56,306 £80,437

(for a 30 sqm extension)

The small but mighty option. To look at, a side return extension isn’t a huge add on to your property, but often generates a lot of new space within your kitchen. Not only that, they can be very reasonable in terms of cost.

Side return extensions bring your property out into an alleyway at the side of your home, if one is present. They’re often added onto period properties, especially those dating from the Victorian era. Side returns help transform your kitchen from a long and narrow space into a square-ish space with ample space to move around, or add a kitchen island. By adding rooflights or even fully glazing the extension, you can also add lots of natural light, making the space feel as bright and airy as it can be. A wonderful and often very popular option to go for.

Talk about your project to a Resi expert.