The short answer
When UK architects charge a percentage of the construction cost, a full service — concept design through to overseeing the build — typically runs at around 7%–15% of the build cost. The exact figure depends on the project size and complexity: smaller and one-off projects sit at the higher end because the work doesn't shrink in proportion to the budget, while larger builds attract a lower percentage. A partial service (for example, design and planning only, with no on-site involvement) is charged at a smaller percentage. The percentage is applied to the construction cost, not the total project cost — it excludes the architect's own fee, VAT, planning fees and other consultants. Because the fee scales with the build, the architect has an interest in the project being well designed, but a fair scope should always be set out in writing.
The percentage model is one of three main ways UK architects bill, and it's common on full-service residential projects. Here's how the calculation works and where the typical numbers sit.
Typical UK percentage fees
- Full service~7%–15% of build cost
- Partial / design onlyLower share
- Smaller projectsHigher percentage
- Applied toConstruction cost only
- ExcludesVAT, planning & consultant fees
How the percentage is calculated
The percentage is applied to the construction cost — the cost of building the work, not the whole project budget. So if a project's build cost is, say, £200,000 and the agreed fee is 10%, the architect's fee is £20,000 plus VAT. A few points that catch people out:
- It's the build cost, not the total spend. Land, planning application fees, the architect's own fee, structural-engineer fees and VAT are not included in the figure the percentage is applied to.
- Estimated then reconciled. Early on the fee is based on an estimated build cost; on many contracts it's adjusted as the real cost firms up, so a higher final build cost means a higher fee.
- Smaller jobs, bigger share. The percentage tends to rise as the project gets smaller, because the design effort doesn't fall away in proportion to the budget.
| Build cost (example) | Fee at ~10% | Fee at ~12% |
|---|---|---|
| £100,000 | ~£10,000 | ~£12,000 |
| £200,000 | ~£20,000 | ~£24,000 |
| £400,000 | ~£40,000 | ~£48,000 |
Illustrative examples only — your percentage and build cost will differ. Excludes VAT. Source: RIBA fee guidance.
What the percentage fee covers
A full-service percentage fee usually covers the architect's involvement across the RIBA Plan of Work stages, broadly:
- Concept and design (RIBA Stages 1–3): developing the brief, options, and the design.
- Planning (within Stage 3): preparing and submitting the planning application drawings.
- Technical design (Stage 4): the detailed and building-regulations drawings needed to build and to satisfy Building Control.
- Tender (Stage 4–5): helping you get and compare builder prices.
- Construction (Stage 5): administering the build, site visits, dealing with queries and certifying payments.
A partial service stops short of some of these — commonly the architect does design and planning, and you take over (or use a different professional) for the on-site stages. A partial service is charged at a lower percentage because it's less work.
Percentage versus fixed and hourly fees
The percentage model has one clear advantage and one clear drawback. The advantage is that it scales automatically: as the project grows, so does the fee, which keeps things proportionate. The drawback is that the final figure isn't fixed until the build cost is, so your fee can drift up if the project gets more expensive.
Some homeowners prefer a fixed fee for exactly that reason — it gives a known total regardless of how the build cost moves. Others are happy with a percentage on larger or more uncertain projects where a fixed price would carry a risk premium. A common arrangement is a fixed fee for the early, defined stages (design and planning) and a percentage for the construction stage, where the workload genuinely tracks the build. Whatever the model, the key is a written fee proposal that lists exactly which RIBA stages are included, what the percentage is applied to, and whether VAT and disbursements are extra.
| Model | Certainty | Best suited to |
|---|---|---|
| Percentage | Varies with build cost | Full-service, larger projects |
| Fixed fee | Known total | Defined scope, tight budgets |
| Hourly | Open-ended | Advice and feasibility |
Indicative comparison of UK architect billing models. Source: RIBA fee guidance.
How to sense-check a percentage fee
Because a percentage fee moves with the build cost, it pays to understand how the number was arrived at and how it might change. A few checks help you sense-check whether a quote is reasonable and budget for the real total:
- Confirm what the percentage is applied to. It should be the construction cost — the cost of the building work — not the total project spend including land, fees and VAT. If a quote isn't explicit about this, ask, because applying a percentage to the wrong base inflates the fee.
- Check the estimated build cost behind the figure. Early on the fee is based on an estimate; a wildly optimistic build estimate makes the fee look low until the real cost firms up. A realistic build estimate gives a more honest fee.
- Ask how the fee is reconciled. On many contracts the fee adjusts as the construction cost is confirmed, so a higher final build cost means a higher fee. Understanding this avoids surprises at the end.
- See which RIBA stages the percentage buys. A 'full service' percentage should cover design, planning, technical drawings, tender and construction administration. A lower percentage may stop earlier, leaving later stages to arrange and pay for separately.
- Add VAT and disbursements. The percentage fee is usually quoted before VAT, and printing or travel may be extra.
None of this means a percentage fee is a worse deal than a fixed one — on a full-service or larger project it's often the fairest model for both sides. The point is simply to know exactly what the percentage covers and what it's calculated on, so the proportionate fee stays genuinely proportionate and the final figure doesn't drift beyond what you planned for. A clear written proposal that states all of this is the sign of a practice you can budget against with confidence.
Frequently asked questions
What percentage do architects charge in the UK?
For a full service from design through to overseeing the build, UK architects on a percentage basis typically charge around 7%–15% of the construction cost. Smaller and one-off projects sit at the higher end; larger projects are lower.
Is the percentage based on the total project cost?
No. It's applied to the construction cost — the cost of the building work itself. It excludes land, planning application fees, VAT, the architect's own fee and other consultants' fees.
Is a percentage fee better than a fixed fee?
Neither is automatically better. A percentage scales with the project and suits full-service or larger jobs; a fixed fee gives a known total and suits a defined scope or tight budget. Many projects use a fixed fee for design and planning and a percentage for the build stage.
Sources & further reading
- RIBA — how much does an architect cost
- HomeOwners Alliance — architect fees explained
- Checkatrade — architect fees guide
Figures on this page are typical UK ranges drawn from published sources and depend on your specific project. They are guidance, not a quotation.