Interior design fee calculator: the same project, billed six ways
Put in your hours, rate and furnishings budget and see what the same project bills under hourly, flat fee, cost-plus, hourly-plus-markup, retail and percentage-of-project — with the effective hourly rate for each.
By Idan Mann, founder of NYA
The short answer
Enter your design hours, hourly rate and the furnishings budget at your cost, and this calculator shows what the same project earns under the six fee models designers actually use — plus the effective hourly rate each one produces. It runs in your browser and asks for no email.
Most fee calculators ask you a question you cannot answer yet — "what should I charge?" — and then answer it with someone else's survey. This one asks what you already know: roughly how many hours the job takes, what your time is worth, and how much the client is spending on furnishings. From those three numbers, the choice of fee model turns out to matter far more than the rate does.
The same project, billed six ways
| Fee model | You bill | Effective $/hour | Client pays in total | Depends on |
|---|---|---|---|---|
| Hourly | $12,000 | $150 | $72,000 | Hours you can actually bill |
| Flat / fixed fee | $13,800 | $172 | $73,800 | How well you scoped it |
| Cost-plus (markup only) | $21,000 | $263 | $81,000 | What the client spends on goods |
| Hourly + markup | $33,000 | $413 | $93,000 | Both — the usual hedge |
| Retail / resale (keystone) | $60,000 | $750 | $120,000 | Goods volume, at double your cost |
| Percentage of project | $9,000 | $113 | $69,000 | Total project cost, including build |
Every figure is computed from the numbers above and nothing else — we publish no industry fee averages, because we have no survey we can source and date. Goods are entered at your trade cost; construction is the builder's number, which you do not mark up unless your contract says you do.
The six models, and what each one really bills for
Hourly
You bill time and pass goods through at cost. It is the fairest model to a client and the one that punishes you for getting faster: every efficiency you gain is revenue you lose. It also caps your income at the hours you can personally work, which is why firms that scale rarely stay purely hourly.
Flat or fixed fee
One number for a defined scope. Clients prefer it because it is a decision they can make once. It rewards you for being fast and destroys you when the scope moves, which is why the calculator applies a contingency to an hourly estimate rather than pretending a flat fee is free of risk — and why a flat-fee agreement needs a change order clause that actually names its triggers.
Cost-plus (markup only)
The client pays your net cost plus an agreed percentage, and you bill nothing separately for time. On goods-heavy projects it out-earns hourly by a wide margin — try a $150,000 furnishings budget in the calculator above. On a consultation-heavy project with a small purchasing budget it earns almost nothing, because your revenue is a function of their spending rather than your work. See cost-plus pricing for what it commits you to disclose.
Hourly plus markup
The common hedge: bill time for the design work, mark goods up for the purchasing work. It is the model most firms converge on, because the two revenue streams fail in different circumstances — a small-budget client still pays for your hours, and a low-touch, high-spend client still pays for your buying power.
Retail or resale method
You quote the client a single price per item and keep the difference between that and your net cost. At keystone — double your cost — that is a 50% gross margin on goods. Nothing is disclosed, which is its advantage and its exposure: a client who discovers the list price feels they have found something out.
Percentage of project cost
A percentage of everything spent, construction included. Common on large renovations and new builds, where the design work genuinely scales with the build. Its weakness is the incentive it creates — your fee rises with the budget — which is why sophisticated clients often ask for it to be capped or converted to a fixed fee once the budget is set.
Which model fits which project
| If the project is… | The models that fit | Why |
|---|---|---|
| Consultation-heavy, low purchasing | Hourly, flat fee | Revenue has to come from time — there are no goods to mark up |
| Large furnishings budget, defined scope | Cost-plus, retail, hourly + markup | Goods carry the fee; time is the smaller cost |
| A full renovation with construction | % of project, or fee + markup | Coordination scales with the build, not with the furniture |
| A repeat client with a vague brief | Hourly | Scope you cannot describe is scope you cannot price |
| A developer or trade client | Flat fee | They are buying a deliverable, and they will hold you to a number |
What this calculator will not tell you
It will not tell you the average rate in your market, because we have no survey we can source and date, and our methodology commits us to not publishing figures we cannot link. Every number above is arithmetic on the numbers you typed. What it will tell you — and what an average never could — is how much revenue you are leaving on the table by choosing one model over another on your own projects.
Common questions
- How do I estimate design hours before I have done the job?
- From your own past projects rather than a formula. Pull three completed jobs of similar scope, add up the hours actually recorded against them, and use the highest of the three. If you have never tracked hours, run the calculator with a range — 60 and 120 — and notice how little the fee models change position relative to each other.
- Should I mark up construction costs?
- Only if your agreement says you do, and most do not — the builder is contracted separately and marking up their invoices is generally a percentage-of-project arrangement wearing a disguise. The calculator therefore leaves construction out of every model except percentage-of-project.
- Do I enter the furnishings budget at cost or at retail?
- At your cost — what you pay the vendor after the trade discount. The calculator derives the client-facing number from your markup, so entering a retail figure would compound the markup twice.
- Is this calculator really free?
- Yes, and there is no email gate. It runs entirely in your browser, we store nothing you type, and there is no report to unlock at the end.