💶 Developer calculation

Does the project pay off? The developer calculation for a Vienna address

A developer calculation sets the revenue of the finished project against every cost: purchase with ancillary costs, construction, planning, marketing, financing. What remains is the surplus — and, as a percentage of total investment, the return. Azima calculates it for one address from what may be built there, with visible assumptions that can be overwritten.

updated November 2026

Worked exampleBurggasse 11, 1070: building class III, measured eaves 13.9 m — an attic conversion with 287 m² of usable area. Total investment 2,244,695 €, revenue 2,439,500 €, surplus 30,000 to 360,000 € at construction costs ±10 %, return +8.7 % on total investment — with the defaults below, as of 12 October 2026.

Does the project at your address pay off? Type the address — Azima reads building class, eaves and footprint, calculates densification and new build and shows surplus, return, residual value and break-even; every assumption can be overwritten, the calculation downloads as CSV.

The address goes to the City of Vienna address service for the search, never to Vienna Living Map. The result stays on this device. No account.

What the calculation contains

Three figures on top — total investment, revenue, surplus — and every item below. The costs: the purchase with transfer tax, registration, contract and commission (together 8.6 %), construction per m² of gross floor area (default 3,000 €, expert range about 2,400 to 4,300 €), surcharges for ancillary costs, planning, structural engineering, marketing and reserve, plus financing (80 % debt at 4.5 % over 24 months). The revenue: the new usable area times the sale price — on a standard floor the district’s official median purchase price in Azima (on this page the default 5,500 €/m²), in the attic a default of 8,500 €/m² that you overwrite. Parking obligation and buy-out follow the zone.

Burggasse 11, 1070: every item

Purchase price509,000 €

Acquisition costs (transfer tax 3.5 %, registration 1.1 %, contract 1 %, commission 3 %)43,774 €

Construction (410 m² GFA × 3,000 €)1,230,000 €

Ancillary construction costs (7 %)86,100 €

Fees planning 7 %, structural 3.5 %, marketing 1.5 %147,600 €

Contingency (5 %)73,185 €

Compensation levy 3 parking spaces (§ 54 WGarG)48,960 €

Financing (80 % debt, 4.5 % p. a. on half the sum over 24 months, processing 0.5 %, mortgage 1.2 %)106,076 €

Total investment2,244,695 €

Revenue2,439,500 €

Surplus (construction ±10 %)30,000 to 360,000 €

Return on total investment+8.7 %

Attic-conversion scenario. Attic purchase price 509,000 € — the middle of the documented market range for raw attics with a building permit (1,350 to 2,200 € per m² of usable area, purchase-contract data to 2021); sale price with the defaults 5,500 €/m² on a standard floor and 8,500 €/m² in the attic — in Azima the district’s median purchase price stands there. Construction cost 3,000 €/m² GFA: residential construction costs in Vienna as recommended by court-appointed experts (TU Wien 2025), indexed to August 2026 with the Statistics Austria construction cost index, range about 2,400 to 4,300 €; interest 4.5 %: 3-month Euribor September 2026 (2.64 %, ECB) plus 2 percentage points; margin 10 % of revenue (literature: 5 to 10 %); other defaults as in common developer calculations (as of 9 Oct 2026); revenue anchor from the district's median purchase price 2025 (Statistics Austria, land register), the attic premium is a default, not a documented Vienna figure; parking obligation by the zone of the Vienna Garage Act 2008; compensation levy under § 54 WGarG — the current rate is published by the City of Vienna. Reference values as of 12 October 2026.

Two houses side by side

Burggasse 11, 1070building class III · 287 m² new usable area

Total investment → revenue2,244,695 € → 2,439,500 €

Surplus (construction ±10 %)30,000 to 360,000 €

Return+8.7 %

breaks even from (attic sale price)7,820 €/m²

Lainzer Straße 125a, 1130building class I · 225 m² new usable area

Total investment → revenue1,773,080 € → 1,912,500 €

Surplus (construction ±10 %)10,000 to 270,000 €

Return+7.9 %

breaks even from (attic sale price)7,880 €/m²

The three levers

Sale price, construction costs and purchase price move the calculation; everything else is a percentage of them. That is why the surplus is never a point but a range for construction costs 10 % higher and 10 % lower — and why Azima shows the three as sliders, each with a mark at the documented reference value. If you want to know the most the purchase may cost, turn the question around: that is the residual value.

Residual value: what may the attic cost?

What the calculation does not know

Rough calculation from the areas of the potential and the stated assumptions — no valuation, no expert opinion, no financing commitment. Not included: condition and statics of the existing building, existing leases, requirements from protection zones or listed-building status, contaminated sites, subsidies, VAT and income taxes, price development over the term. Interest is calculated on half the loan over the term (average drawdown). Construction cost 3,000 €/m² GFA: residential construction costs in Vienna as recommended by court-appointed experts (TU Wien 2025), indexed to August 2026 with the Statistics Austria construction cost index, range about 2,400 to 4,300 €; interest 4.5 %: 3-month Euribor September 2026 (2.64 %, ECB) plus 2 percentage points; margin 10 % of revenue (literature: 5 to 10 %); other defaults as in common developer calculations (as of 9 Oct 2026); revenue anchor from the district's median purchase price 2025 (Statistics Austria, land register), the attic premium is a default, not a documented Vienna figure; parking obligation by the zone of the Vienna Garage Act 2008; compensation levy under § 54 WGarG — the current rate is published by the City of Vienna. Reference values as of 12 October 2026.

Azima dollhouse view of the example address Schrankgasse 10: the measured house from above, the flat opened, sun position and shadows. — **And your project?** For one address, Azima calculates extra storeys, attic conversion and new build — total investment, revenue, surplus as a range, return, residual value and break-even, starting from the district’s median purchase price. Every assumption can be overwritten; the project stays in the browser, the calculation downloads as CSV. Check your own address →

Frequently asked

What is a developer calculation?

The comparison of a building project’s revenue with all its costs — purchase and ancillary costs, construction, planning, marketing, financing. The result is the surplus in euros and, as a percentage of total investment, the return. It decides whether a project is started at all.

Which costs belong in it?

Purchase price plus acquisition costs (transfer tax, land register, contract, commission — together about 8.6 %), construction per m² of gross floor area, ancillary construction costs, planning and structural engineering, marketing, a reserve and the financing of all of it over the construction period. Azima lists every item with its amount.

Does densification pay off in Vienna?

It depends on building class, eaves and sale price. For Burggasse 11, 1070 (building class III) the calculation gives a surplus of 30,000 to 360,000 € on 2,244,695 € total investment, a return of +8.7 %; for Lainzer Straße 125a, 1130 (building class I) 10,000 to 270,000 € and +7.9 %. Both with the defaults shown — your sale price and your construction costs decide.

What return is usual?

The literature names 5 to 10 % of revenue as the developer’s profit; Azima’s target margin for the residual value is 10 %. A single figure says little — the surplus is shown as a range because construction costs alone vary by about 40 % between expert values.

Is this a valuation or a financing commitment?

No. It is a rough calculation from open data and stated assumptions — no valuation, no appraisal, no financing commitment, no building permit. It tells you whether it is worth taking the next step.

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