How much does an architect cost for an extension in the UK?
An architect costs £3,500 on average in the UK. Most jobs fall between £1,200 and £9,000 for an extension. Service level: Planning drawings only £1,200 to £2,500; Planning + building regs drawings £2,500 to £5,000; Full service £4,000 to £9,000. Prices reviewed July 2026.
Architect fees for a home project are charged either as a fixed fee for the drawings or as a percentage of the build cost for a full service. What you pay depends on how much of the project they run.
Architect cost calculator
Use the calculator to price your architect in 2026. Adjust the options and area for a UK cost range. Nothing is sent anywhere.
Architect cost breakdown
Typical architect costs, by option:
| Service level | Typical UK cost |
|---|---|
| Planning drawings only | £1,200 to £2,500 |
| Planning + building regs drawings | £2,500 to £5,000 |
| Full service, design to completion | £4,000 to £9,000 |
| + Measured survey or 3D visuals | add £300 to £900 |
| + Structural engineer's calculations | add £500 to £1,200 |
What's included in the price?
Typical architect prices include:
- Design and drawings for the project
- Drawings for planning permission or building regulations
- Advice on layout, light and materials
- Submitting the planning application where agreed
What changes the price?
The things that move architect prices most:
Drawings only versus a full design-to-completion service
A fixed fee versus a percentage of the build cost
An architect versus an architectural designer or technician
The size and complexity of the project
These are why two quotes for the same job can differ, and the only way to know your price is to get prices from local firms (through Bark; we may earn a fee, at no extra cost to you).
Does where you live change the cost?
In London, an architect typically costs around £4,200 for an extension, about 20% above the UK average of £3,500. In the North, Scotland and Wales the guide figure is nearer £3,400.
| Region | From | Typical | Up to |
|---|---|---|---|
| Midlands / East (UK average) | £1,200 | £3,500 | £9,000 |
| London | £1,400 | £4,200 | £11,000 |
| South East / South West | £1,300 | £3,700 | £9,500 |
| North / Scotland / Wales | £1,200 | £3,400 | £8,700 |
Guide prices for an extension, scaled with the same regional multipliers as the calculator. Not quotes.
Architect cost in major UK cities
| City | From | Typical | Up to |
|---|---|---|---|
| Belfast | £1,100 | £3,300 | £8,600 |
| Birmingham | £1,200 | £3,500 | £9,000 |
| Bristol | £1,300 | £3,700 | £9,500 |
| Cardiff | £1,200 | £3,400 | £8,700 |
| Edinburgh | £1,200 | £3,400 | £8,700 |
| Glasgow | £1,200 | £3,400 | £8,700 |
| Leeds | £1,200 | £3,400 | £8,700 |
| Liverpool | £1,200 | £3,400 | £8,700 |
| London | £1,400 | £4,200 | £11,000 |
| Manchester | £1,200 | £3,400 | £8,700 |
| Newcastle | £1,200 | £3,400 | £8,700 |
| Sheffield | £1,200 | £3,400 | £8,700 |
City guide estimates, scaled by local labour costs. Indicative averages for architect, not quotes.
In London and the South East, figures run well above the national figures on professional fees.
Compare this with a real quote
The figures above are guide prices. Two or three quotes from local architects tell you what it costs where you live.
Free and no obligation. You answer a few questions on Bark, local pros get in touch, and you decide who, if anyone, to hire. We may earn a fee, at no extra cost to you.Common questions
How much are architect fees for an extension?
An architect costs roughly £1,200 to £9,000 for a home extension in the UK, typically around £3,500. Planning drawings alone are £1,200 to £2,500, planning plus building regulations drawings £2,500 to £5,000, and a full service from design through to overseeing the build £4,000 to £9,000, or often 8 to 15 percent of the build cost.
How are architect fees calculated?
Two ways are common. A fixed fee covers a defined package, such as the drawings for planning and building regulations. A percentage of the build cost, usually 8 to 15 percent, covers a full service that runs from design through to inspecting the build. Smaller pieces of work are sometimes charged by the hour. Always get the fee proposal to state which it is and what stages are covered.
Do I need an architect for an extension?
Not legally. For a straightforward rear extension, an architectural designer or technician can produce the drawings for planning and building regulations for £1,200 to £3,000, which is often all you need. An architect registered with the Architects Registration Board adds design skill and can manage the whole project, which earns its higher fee on complex, unusual or planning-sensitive builds.
Is it worth getting an architect for an extension?
For a simple, box-shaped extension, good drawings from a designer may be enough. An architect is worth the higher fee when the site is awkward, the design is ambitious, you are in a conservation area, or you want someone to manage the builders and inspect the work. Match the professional to the ambition of the project rather than paying for a service you do not need.
What do architect fees include?
It depends on the package. A drawings-only fee covers the plans for planning permission and, if included, building regulations. A full service adds detailed design, help choosing and pricing a builder, and site inspections during the build. Architects work in stages, so the fee proposal should spell out exactly which stages are included and which are extra.
Do architect fees include planning permission and structural calculations?
Usually the architect prepares and submits the planning application, but the council's application fee is separate and paid by you. Structural engineer's calculations are normally a separate cost of £500 to £1,200 on top, as is the building control charge. When comparing quotes, check what is inside the architect's fee and what you will pay for separately, so you compare like for like.
Can I do my own drawings instead of hiring an architect?
You can for small, simple jobs, and it saves the £1,200 to £2,500 you would pay for planning drawings. But for an extension the drawings guide the whole build, so mistakes get built in and cost far more to fix. If you are not confident with scaled plans, planning rules and building regs, paying a professional is usually money well spent.
How do I check someone is really an architect?
Look them up on the Architects Register, which the Architects Registration Board (ARB) keeps online, using the registration number any architect can give you. Under section 20 of the Architects Act 1997 only a registered person may practise or carry on business under a title containing the word 'architect', and misuse is an offence under section 21, which ARB says can mean a fine of up to £2,500 for each offence. RIBA or similar membership is voluntary and is not what makes someone an architect. Anyone may legally provide architectural services, so a designer who does not use the title is breaking no law.
Check they are registered before they start
The title architect is protected by law, but the work is not: anyone may offer design services. If someone calls themselves an architect, they must be on the register. Checking takes about a minute and it is free.
- Search the Architects Register Architects Registration Board · The statutory register. Only people on it can use the title architect in business, so search by name or registration number before you sign a fee proposal
Official guidance and sources
The rules and schemes referenced on this page come from these official UK sources. The price figures are Costwise's own; see how we price.
- Before hiring an architect Architects Registration Board · Only people registered with ARB can legally use the title architect, membership of bodies such as RIBA is voluntary, and there is no restriction on who can provide architectural services.
- Architects Act 1997, section 20 legislation.gov.uk · A person may not practise or carry on business under any name, style or title containing the word architect unless they are registered.
- Architects Act 1997, section 21 legislation.gov.uk · Makes misuse of the title an offence, punishable by a fine on summary conviction.
- What we do to regulate the use of the title architect Architects Registration Board · How ARB enforces the protected title, including a fine currently up to £2,500 for each offence.
Cite this data
These figures are free to use in articles, reports and research under a CC BY 4.0 licence. All we ask is a credit to Costwise, and online a link. Where your style allows, please make "Costwise" the linked word so readers can check the figure for their own region.
Costwise (2026): An architect typically costs £3,500 in the UK, ranging from £1,200 to £9,000 for an extension. Reviewed July 2026. costwiseuk.co.ukSource: Costwise (costwiseuk.co.uk)Costwise (2026). Architect cost. Costwise UK cost data, version 2026-10-05. https://costwiseuk.co.uk/architect-cost/2026-10-05 (158 jobs)Dataset DOI: 10.5281/zenodo.21159943 · also on Kaggle, Hugging Face and Figshare. Method: how we price. Downloadable CSV.
These are independent guide prices based on typical UK jobs in 2026. Your actual cost depends on your property, spec, access and where you live. Always get at least three written quotes before committing.