Interior design pricing models compared: hourly, flat, percentage, cost-plus and hybrids (with break-even maths)

What are the main interior design pricing models?

Sources such as HoneyBook, Houzz and The Little Design Corner describe the same family of models, though they disagree on typical rates, so this page compares structure and risk rather than quoting ranges. Last reviewed: 30 October 2026.

For how to record these in a Fees database, see the mark-up and retainer page; for writing the proposal, the fee proposals page. This page is about choosing between them.

• Mark-up and retainer tracking
• Fee proposals that get signed

How do the models compare on the same project?

Fictional project: a three-room living area. Estimated design effort 120 hours; target rate $100 an hour; $50,000 of products at trade cost. Assume the studio's fully loaded cost per hour is $75 (see the break-even maths in the profitability guide). Real effort turns out to be 160 hours, a 33% overrun. To compare fairly, models one to three pass products through at cost with no mark-up; the cost-plus and hybrid models include it.

Reading the table. The flat fee breaks even only because the estimate was priced at cost-per-hour; at the target rate it was still a 25% discount once the overrun hit. The percentage fee loses money because the budget, not the effort, set the price. The hybrid does best here because the mark-up earns on the product value while the design fee covers most of the planned effort, but it is also the model where procurement hours are most likely to be underestimated. Change the overrun to zero and the ranking shifts, so run your own numbers.

How do you choose? A 5-question decision tree

1. 1

   Is scope clear and bounded?

   If yes, a flat fee or hybrid is workable. If not, start hourly with an estimate and cap, then convert to a fixed fee at the next phase once scope firms up.

2. 2

   Do you have data on your hours for this project type?

   If you do not, avoid a flat fee. Use hourly or a fixed fee for phase one only, and log time.

3. 3

   Will you purchase for the client?

   If so, add cost-plus or mark-up and be explicit about it. If the client buys directly, you need a design fee that covers the whole job.

4. 4

   Is the client likely to change direction?

   If yes, favour hourly or a tight revision limit with change orders.

5. 5

   Does the budget reflect the work?

   Percentage models only make sense when spend is a decent proxy for effort. A small budget with a complex room is where it fails.

Who bears the risk in each model?

Every model allocates three risks: effort overrun, budget change and sourcing cost. Writing this down helps clients understand why you are proposing a given structure.

How do you convert a model into a number you can defend?

Work in this order: (1) compute your cost per hour; (2) estimate hours from your own logs by phase; (3) multiply by your target rate; (4) add a contingency; (5) compare the result with the model's output, for example the percentage of project cost; (6) choose the higher of the model's price and your cost-based floor, or explain to yourself why you are accepting less.

For the example project: 120 hours x $100 = $12,000. A 15% contingency for revisions adds $1,800 for $13,800. If a 20% percentage fee yields only $10,000, a pure percentage proposal would be $3,800 below your cost-based price. That is the signal to change the model, raise the percentage for this project or reduce the scope.

• Effective hourly rate, utilisation and overhead
• Scope creep and change orders

Where InteriorDesignOS fits

We make InteriorDesignOS, a Notion template, so weigh our view accordingly. InteriorDesignOS is a $39 one-time Notion template with a Fees & Invoices database and a projects view showing construction value and amount invoiced. It lets you record what you agreed and what you invoiced under any model. It does not calculate fees, check your pricing, process payments or produce legal invoices; those stay with your own judgement and accounting software.

• InteriorDesignOS
• Pricing
• Run the whole practice

Frequently asked questions

What are the common interior design pricing models?

Hourly, flat (fixed) fee, percentage of project cost, cost-plus (mark-up on purchased products) and hybrids that combine a design fee with mark-up. Many designers use a hybrid for full-service residential work.

Is flat fee or hourly better for interior design?

Neither is universally better. Hourly puts the risk of overrun on the client and suits uncertain scope; a flat fee suits clear scope and gives clients certainty, but the studio carries overruns. Use your own time data to decide.

How do I price an interior design project?

Estimate hours by phase from your own records, multiply by a rate at or above your cost per hour, add a contingency, and compare with percentage or cost-plus outputs. Then choose the model that allocates risk sensibly for that client.

What is cost-plus pricing in interior design?

You buy products at trade cost and sell them to the client at cost plus a mark-up. The mark-up pays for sourcing, ordering and handling. Mark-up is a percentage of cost; margin is a percentage of the selling price, so label which one you quote.

Can I mix pricing models on one project?

Yes. A fixed design fee plus mark-up on furnishings, or a fixed concept fee followed by hourly development, are common patterns. Make the structure explicit in the proposal, including how changes are priced.