Get a personalised garden room estimate
Averages only tell you so much — the real cost of your garden room depends on your exact size, specification, and what’s inside it. Use the calculator below for an instant estimate, then leave your details if you’d like a firm, no-obligation quote.
Garden room cost calculator
Move the sliders and toggles to match your project — the estimate updates instantly.
Typical price bands by configuration
If you’d rather skip the sliders, here’s roughly where most UK builds land by configuration:
| Configuration | Typical size | Estimated cost |
|---|---|---|
| Basic uninsulated garden room | 4.5m²-7.5m² | £5,000-£10,000 |
| Insulated garden office (electrics, no bathroom) | 9m²-12m² | £15,000-£22,000 |
| Insulated garden gym or studio | 9m²-15m² | £16,000-£25,000 |
| Garden room with bathroom | 12m²-18m² | £25,000-£40,000 |
| Garden room with kitchen and bathroom | 18m²-24m² | £35,000-£55,000 |
| Bespoke garden annexe (full living space) | 25m²+ | £50,000-£100,000+ |
These figures are indicative UK averages for a professionally installed, fully specified build — see our Garden Room Cost UK guide for the full breakdown of what drives price up or down, including size, material, and hidden costs like groundworks and electrics.
What changes your number most
Size is the single biggest factor — most companies price per square metre, so every extra square metre adds a predictable amount. See the size-by-size breakdown in our main cost guide.
Insulation and glazing — a basic timber shell costs meaningfully less than a fully insulated, double-glazed room built for year-round use. If you want to use the space through a UK winter, insulation isn’t optional — see our Insulated Garden Room Guide.
Plumbing — adding a bathroom or kitchen means groundworks for drainage, which is one of the largest single cost jumps in this list. Our Garden Room With Bathroom Cost guide breaks this down in detail.
Electrics — running a supply from your house, a separate consumer unit, and internal wiring is a real cost most headline prices don’t fully show. See our Garden Room Electrics guide.
Foundations — the base type (concrete pad vs. screw piles) varies by ground conditions and affects cost — see our Garden Room Foundations guide.
Planning permission — most garden rooms don’t need it, but if yours falls outside permitted development (see our Planning Permission guide), application costs and delays add to the project.
Why this is an estimate, not a quote
Every UK garden room company prices slightly differently, and ground conditions, access, and local labour rates all shift the final figure. The calculator above gives you a realistic planning range based on typical UK pricing — the next step for a firm number is getting a real quote from a company who can see your actual garden, your access, and your specification.
Want a firm quote?
Leave your details below and tell us a bit about your project. This isn’t an automated installer-matching service — a real person reads every enquiry and follows up personally, so response times may vary. No obligation, and it costs nothing to ask. See our privacy policy for how we handle your details.
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Frequently asked questions
How accurate is a garden room cost calculator? A calculator or reference table like this one gives you a realistic range based on typical UK pricing, but your exact cost depends on your garden’s access, ground conditions, and specification — always confirm with a real quote before budgeting precisely.
Is it free to get a garden room quote? Yes — leaving your details costs nothing and doesn’t obligate you to proceed with anyone. We follow up personally rather than auto-matching you to installers.
How many quotes should I get for a garden room? Most buyers compare at least three quotes before choosing an installer, since prices and specifications can vary meaningfully between companies for what looks like the same job — see our How to Choose a Garden Room Company guide.
*Related guides: Garden Room Cost UK · Garden Room With Bathroom Cost · Insulated Garden Room Guide · Garden Room Planning Permission*