Which model fits depends on whether you need a concept or someone alongside you until move-in. In every case you should receive a proposal that names the scope before you commit. Below you will find the usual fee models, what pushes the price up or down, and a list of questions to test a proposal against.
The exact figure depends on the scope. A colour scheme for a living room is a small job. The complete interior design of a period apartment with bespoke joinery and site supervision is many times that.
The three fee models in interior design
Share of the cost. The fee is calculated as a percentage of the eligible cost, meaning what conversion, fit-out and built-ins cost. In Germany this is the logic of the HOAI, which has its own section for interiors. The advantage: the fee scales with the project and the scope is clearly described through work stages. The drawback: a designer who plans frugally earns less. The model still works well as long as the studio shows you its cost estimate.
Hourly rate. Sensible for advice, for a concept without execution, or for support on individual decisions such as material choices. An hourly rate is only fair when it comes with an estimate of the hours. Otherwise you only learn what the advice cost when the final invoice arrives.
Fixed fee per work stage. Concept, design, construction drawings, tendering, site supervision and furnishing are priced separately. You see what each stage costs and can decide after each one whether to continue. For private homes this is often the most transparent model. In practice, hybrids are common: a fixed fee for planning, an hourly rate for changes you request after sign-off.
What drives the price of an interior designer
Four factors have the biggest effect on the fee.
- Scope. A concept with mood board and a layout option is a fraction of what planning through to handover costs. The HOAI describes nine work stages from initial appraisal to post-completion care. Settle first which ones you need. If you are unsure whether you need an interior designer or an architect at all, this comparison helps.
- Floor area and existing fabric. More area means more drawings and more coordination with the trades. A period building also needs a survey, because old plans rarely match what was built.
- Level of detail. Bespoke joinery, special surfaces, lighting design and custom-drawn details call for shop drawings and sampling. This is usually where most of the design hours go.
- Site supervision and furnishing. Whoever attends the site, checks quotes and procures furniture works for months. Ask whether that is included in the proposal and how procurement is billed.
Then there is location. A project on Mallorca for owners who live abroad requires travel, weekly reports and collaboration with a locally registered architect for permits. That work should be priced into the fee so it does not turn up later as expenses. How the remote model works is described in our piece on renovating in Mallorca from abroad.
Where the fee sits in the overall budget
For comparison, here is what the building work costs. As a rough guide, a full Altbau renovation in Berlin runs about 1,500 to 3,000 euros per square metre, a finca or townhouse on Mallorca about 1,200 to 2,500 euros per square metre. What that means in detail for a Berlin Altbau renovation or a finca on Mallorca we have written up separately.
At CARLO Design the fee for design and planning is 10 to 15 percent of the construction cost. Project management and site supervision are charged on top. The larger the project, the smaller that share, because the work does not double with every square metre. On small projects it comes out higher: a small apartment with less expensive furniture takes almost as much planning as a large one with costly pieces, while the construction cost is much lower. As an example, for a 200,000 € renovation the planning fee is 20,000 to 30,000 €.
Against those sums, the designer's fee is the smaller item, but it affects how large the big ones turn out. A layout that works first time saves you a second round of building work a few years later. A tender in which every position is listed makes quotes comparable. How to tell whether a contractor's quote holds up is covered in red flags in contractor quotes.
Where planning saves money
Fees tend to be seen as pure cost. Across more than 40 projects since 2015, we have seen planning save money in four places.
- Changes during construction. Every decision made on paper costs a fraction of what it costs on site.
- Comparing quotes. Contractors price on the same basis when the tender is unambiguous. Without planning you are comparing estimates.
- Buying materials. A studio knows where to source good natural stone, timber and fittings, and where you would only be paying extra for a brand name.
- Lasting value. Rooms planned around daily routines and daylight wear better and are easier to sell or let.
How to read a fee proposal
A good proposal answers seven questions without you having to ask.
- Which work stages are included, and which are not?
- What is the basis of calculation: construction cost, hours or a fixed fee?
- How are changes after sign-off billed?
- Are travel, reproductions and specialist consultants such as structural or lighting engineers included?
- Is site supervision included, and how often, for instance weekly visits?
- How is furniture procurement billed?
- What is the payment schedule, and when can you step out?
If any of these remains open, ask. A reliable studio can tell you how it arrived at its figure.
How we talk about fees at CARLO Design
As a guide, planning costs 10 to 15 percent of the construction cost. We make a firm fee proposal once we have seen your rooms, because without scope and floor area the exact figure would be a guess. The starting point is the Project Check. We come to you in Berlin or on Mallorca, walk through the rooms and talk about what you have in mind. How to prepare for it is in our piece on the first meeting with your architect.
You then receive a design direction, a cost frame for the works and a fee proposal that names each work stage. Only then do you decide. That is how our team works as an interior designer in Berlin and as an interior design studio on Mallorca, and it is how a project with us runs.
FAQ
How much does an interior designer cost per hour?
Hourly rates vary widely with experience, city and the type of task, which is why serious studios quote them together with an estimate of the hours involved. The rate matters less than the number of hours a concept or a set of construction drawings takes, and which documents you have at the end. Ask for both and proposals become comparable.
Is an interior designer worth it for a small apartment?
Yes, if the apartment should work better day to day than it does now. In a small space, layout, storage and light make the biggest difference, and planning them is cheaper than trial and error. A small apartment usually suits a limited scope: concept and construction drawings, with your own contractors doing the work. The fee is then a larger share of the construction cost than on a big project, because the planning takes almost as much work.
Is the fee included in the construction cost?
No. Construction cost and fee are two separate items. The construction cost pays for trades and materials, the fee pays for planning and supervision. If a studio procures furniture, the proposal should state how that work is billed.
Does the HOAI apply to interior designers?
The German HOAI has its own section for interiors and describes work stages from initial appraisal to post-completion care. Since 2021 it no longer sets binding minimum or maximum rates, so fees are agreed freely. As a description of what a planning service covers, it remains the common reference in Germany. It does not apply on Mallorca, where the contract defines the scope.
How do I find out what my project would cost with CARLO Design?
As a guide, allow 10 to 15 percent of the construction cost for planning, plus project management and site supervision. The exact proposal follows the Project Check. We visit you, look at the rooms and talk about scope, floor area and timing. You then receive a design direction, a cost frame for the works and a fee proposal that names the work stages. The Project Check carries no obligation.
Your next step
If you want to know what your project would cost, send us a few lines: apartment or house, floor area, what should change and by when. We will come back to you with a date for the Project Check.
For a rough figure on your own project, use the two-minute calculator. Open the cost and timeline calculator.