Interior designer fees: how they are calculated
Interior design fees are calculated in three ways: as a percentage of the works between six and twelve per cent, per square metre between twenty and sixty euros, or as a fixed fee for a defined project.
gelisted editorial team · Updated 15 August 2026
The short version
- The percentage on works runs 6 to 12 per cent.
- Price per square metre of project runs 20 € to 60 €.
- Hourly consultancy runs 80 € to 150 €.
- Site supervision is usually billed separately from the project.
The question is not how much they charge but what is being bought. A drawing is not a project, and a project is not somebody visiting the site every week.
The three models
A percentage of the works value aligns the fee with the real scope and is the usual arrangement on full renovations. A price per square metre suits a commission for drawings and documentation without site supervision. And a fixed fee fits contained commissions: a layout for a home, a kitchen project, or the selection of finishes and furniture.
| Model | Range | Suits |
|---|---|---|
| Percentage of works | 6 to 12 % | full renovation |
| Price per square metre | 20 to 60 € | project without supervision |
| Fixed fee for a project | 1,500 to 8,000 € | contained commission |
| Hourly consultancy | 80 to 150 € an hour | one off advice |
| Site supervision | 3 to 6 % additional | weekly visits |
| Additional renders | 150 to 400 € each | |
| Purchasing management | 5 to 15 % of the spend | optional |
What the commission should include
A survey of the existing condition. A layout proposal with at least 2 alternatives. Construction drawings with dimensions, service heights and lighting points. A specification naming materials with concrete references. And joinery details where relevant. Without service drawings and a specification the project is not buildable, and the decisions end up being taken on site, which is where they cost.
When it pays for itself
On works above 40,000 €, a properly resolved project prevents changes during construction, which is the line that most derails a budget. Moving a water point after the tiling is done costs 400 € to 900 €; remaking a badly measured wardrobe costs 800 € to 2,500 €. Two or three such decisions avoided cover the fee on a 3,000 € to 5,000 € project.
Purchasing management often secures terms that recover a meaningful part of its own cost.
What to agree in writing
The exact scope with a list of deliverables. The number of revisions included, usually 2 or 3, and the price of further ones. The programme with delivery dates. The payment structure, normally in milestones of 30, 40 and 30 per cent. And whether site supervision is included or contracted separately, stating the number of visits foreseen.
Frequently asked
+What does an interior designer charge?
Six to twelve per cent of the works, 20 € to 60 € per square metre of project, or a fixed fee.
+What should they deliver?
Survey, layout proposal, drawings with dimensions and services, and a materials specification.
+Is site supervision included?
Usually not. It is billed separately at an additional 3 to 6 per cent.
+When is it worth engaging one?
On works from 40,000 €, where avoiding two or three site changes covers the fee.
+How is it paid?
In milestones, commonly three payments of 30, 40 and 30 per cent of the agreed amount.
Sources
- 1Boletín Oficial del Estado, BOE (August 2026)
- 2Govern de les Illes Balears, Govern de les Illes Balears (August 2026)