Kitchen Extension Cost Calculator
Most kitchen extension quotes cover the shell and stop. This prices the shell and the fit-out separately, so you see the number you will actually spend.
Open the calculator →Price a kitchen extension in 30 seconds
5 steps. Covers floor area, shell spec, the kitchen itself, glazing and region.
How this calculator works
A kitchen extension is two budgets that people routinely conflate. The shell is priced per square metre by your builder. The kitchen is a separate purchase with a range so wide — £4,000 to £35,000+ — that folding it into a per-m² rate makes the number meaningless.
The regional multiplier is applied to the build only. Units and appliances cost much the same in Leeds as in London; it is the labour that moves. Our cost guide’s worked 20m² example totals £47,500 with a mid-range kitchen, which is where this calculator lands on the same inputs.
Kitchen extension costs, worked example (2026)
| Element | Typical 2026 cost | Notes |
|---|---|---|
| Extension shell (20m²) | £36,000 | At £1,800/m² |
| Kitchen units and worktops | £5,000 | Mid-range |
| Appliances | £1,800 | Integrated |
| Flooring | £1,200 | LVT, tile or engineered wood |
| Bifold or sliding doors | £3,500 | |
| Total, 20m² kitchen extension | £47,500 | Excluding fees and contingency |
Worked example from our kitchen extension cost guide. A high-end kitchen can add £20,000+ to the same shell.
Kitchen extension calculator FAQs
Usually not. Most builders quote the shell — structure, roof, glazing, plastering, sometimes flooring — and leave units and appliances to you. Always check what "finished" means in a written quote; this is the single most common budgeting gap on this type of job.
£4,000–£7,000 for budget, £9,000–£16,000 mid-range, £20,000+ for high end, including worktops and appliances. It is worth choosing the kitchen early even if it is fitted last, because unit layout drives where services need to run during first fix.
On a deep plan, yes. Anything beyond about 4m deep gets gloomy at the back with only rear glazing, because light falls off quickly from the doors. Overhead glazing lights the middle of the room, which is usually where the island ends up.
Yes, and most people do. Budget for the drainage and gas runs, which are easier to plan at first fix than to retrofit. If you are moving the boiler as part of it, that is notifiable work — see our central heating calculator for what that adds.
Related cost guides
- Kitchen extension guide — full 2026 pricing
- Kitchen cost calculator — price the fit-out on its own
- Extension cost calculator — price the shell alone
- House extension costs — every type compared
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