Cost per m² Calculator: Build Cost and Break-Even Price
1. Short answer
Construction cost per square metre is the build cost divided by the project's floor area. It is the figure that shows at a glance whether a refurbishment is in proportion to what it produces.
Construction cost per m² = construction costs ÷ project floor area
A scheme with € 450,000 of build cost across 260 m² comes out at € 1,731 per m². Three related figures sit alongside it and are routinely confused: total cost per m², sales price per m² and the break-even sale price per m². They do not all divide by the same area, and that is deliberate.
2. Four figures, two denominators
The per-square-metre family consists of four metrics that look alike and answer different questions.
| Metric | Numerator | Denominator |
|---|---|---|
| Construction cost per m² | Build cost only | Project floor area |
| Total cost per m² | All project costs including interest | Project floor area |
| Sales price per m² | Gross sales revenue | Sellable floor area |
| Break-even sale price per m² | Costs, with the agent fee grossed up | Sellable floor area |
The cost side divides by project floor area: the whole building, including the stair core, storage and common parts. That is what you refurbish and what you pay for.
The sales side divides by sellable floor area: the sum of the units you actually sell. A buyer pays per sellable square metre and does not pay for the stair core.
What BRIX Calc does. Those two denominators sit side by side on purpose. The break-even sale price is placed on the sales side even though it is a cost figure: only then do "what I ask" and "what I have to ask" sit on the same ruler. Put break-even on the project area and you would be comparing two numbers that are not comparable by construction.
Where area is lost, the difference is measurable. Lose 25 of 260 m² to circulation and the cost per sellable metre rises by more than € 300 without a single euro of cost being added.
3. The formula, component by component
Construction costs. Build only. Professional fees, architect, statutory charges and contingency fall outside it and do sit in total costs. That makes construction cost per m² useful for comparing contractor quotes and useless for deciding whether the scheme works.
Total costs. Acquisition, build, professional fees, statutory charges, contingency and the interest you pay or roll up during the project. The selling agent fee is not in it: you only pay that at the sale.
Break-even sale price. This is the trap most spreadsheets fall into. Break-even is not total costs divided by area, because an agent fee comes off your sale proceeds. You therefore have to ask for more than your costs to break even:
Break-even revenue = total costs ÷ (1 − agent fee percentage)
At a 2% fee that means a mark-up of slightly more than 2% on your costs, not exactly 2%. Deduct the fee from proceeds instead of grossing it up and your break-even is structurally too low.
Value per m² on a rental property. The rental calculator carries a fifth figure: value per m². It runs on vacant possession value rather than on value in let condition, because the Dutch market quotes a price per square metre on vacant possession. LTV meanwhile runs on the value in let condition. Those are two different value concepts on the same screen, and the gap is on the order of fifteen percent.
4. Worked example
The same development project as on the ROI page: a vacant 260 m² office building converted into four apartments totalling 235 m² of sellable area. Figures in euros, on Dutch rules.
| Item | Amount |
|---|---|
| Construction costs | € 450,000 |
| Total project costs including interest | € 823,200 |
| Sales revenue | € 950,000 |
| Selling agent fee | 2% |
| Project floor area | 260 m² |
| Sellable floor area | 235 m² |
Construction cost per m² = 450,000 ÷ 260 = € 1,731 Break-even sale price per m² = (823,200 ÷ 0.98) ÷ 235 = € 3,574
| Metric | Value | What it means |
|---|---|---|
| Construction cost per m² | € 1,731 | Build only, across the whole project area |
| Total cost per m² | € 3,166 | Including acquisition, fees, charges, contingency and interest |
| Sales price per m² | € 4,043 | What you ask, across the sellable area |
| Break-even sale price per m² | € 3,574 | The least you can ask and still break even |
| Margin per m² | € 468 | The gap between what you ask and what you must ask |
The comparison you must not make is € 3,166 against € 4,043. Those sit on different areas and the first ignores the agent fee. The gap between them decomposes into three steps:
| Step | Per m² | What is added |
|---|---|---|
| Total costs ÷ project area | € 3,166 | Cost price as you budget it |
| Total costs ÷ sellable area | € 3,503 | The 25 m² of lost area |
| Break-even sale price per m² | € 3,574 | The selling agent fee, grossed up |
Sensitivity. A 10% build overrun adds € 45,000 and moves break-even from € 3,574 to € 3,770 per m². Margin per m² almost halves, from € 468 to € 273. On a scheme of this size a 10% overrun is not a blemish but the difference between a reasonable and a marginal result.
5. What is a reasonable cost per m²?
Build costs per square metre vary widely with the type of intervention. Indicative ranges for Dutch residential conversion in 2026, not a published standard:
| Type of work | Indication per m² |
|---|---|
| Cosmetic: decoration, floors, kitchen and bathroom | € 400 to € 900 |
| Refurbishment with a new layout and services | € 900 to € 1,600 |
| Conversion with structural work and new services | € 1,500 to € 2,500 |
| New build behind a retained facade | € 2,000 to € 3,000 |
Ask of every quote whether the figure is on project area or sellable area, and whether fees and statutory charges are inside it. Two contractors both saying "€ 1,700 per m²" can be tens of thousands apart on those two answers alone.
6. Three mistakes that distort the number
Putting cost and revenue on the same area. That hides the lost area. On this project it is 25 m², worth € 337 per sellable metre.
Deducting the agent fee from proceeds instead of grossing it up. Break-even then comes out € 71 per m² too low, which sounds trivial until you spread it over 235 m².
Using construction cost per m² as a decision figure. It says nothing about the purchase price, the statutory charges, the contingency or the interest. To judge whether a scheme works you need total cost per m², the break-even, and then the ROI.
7. Run your own numbers
Enter your own figures above and all four numbers move together. To model the whole scheme, with phases, financing and a line-by-line cost breakdown, use the BRIX Calc development calculator.
8. Frequently asked questions
Which floor area belongs in the denominator?
It depends on the figure. Cost metrics divide by project area, because that is what you refurbish; sales metrics divide by sellable area, because that is what a buyer takes. Put both on the same denominator and the lost area disappears from view, and that is exactly the item that quietly turns a scheme unprofitable.
Are professional fees inside construction cost per m²?
No. BRIX Calc computes construction cost per m² on build cost alone, without architect, engineer, statutory charges or contingency. Those do sit in total cost per m². The gap on this project is large: € 1,731 against € 3,166 per m², though the latter also carries the purchase price of the building.
Why is the break-even sale price higher than total cost per m²?
For two reasons at once. Break-even divides by the smaller sellable area, and it grosses the selling agent fee back into the revenue you need. On this project € 337 of the gap is lost area and € 71 is the fee.
Why does BRIX Calc put the sales price on a different area from the costs?
Because a buyer pays per sellable square metre. Put sales price on the project area and a scheme with a lot of circulation would show a lower price per m² than it actually achieves, and the lost area would appear as a discount on your sale price rather than as a cost.
What is value per m² on a rental property?
Vacant possession value divided by area, which is a different basis from the one LTV uses. Vacant possession value is what the property fetches sold empty; the value in let condition is lower because a buyer inherits a sitting tenant. The Dutch market quotes a price per square metre on vacant possession, so BRIX Calc does the same.
Can I judge a quote on construction cost per m²?
As a first filter yes, as a verdict no. Always ask whether the figure is on project or sellable area, what is and is not included, and whether it is a fixed contract sum or a guide price. Two quotes at the same rate per m² can cover completely different scopes.