Renovation Cost Calculator: What does a renovation cost?

A comprehensive renovation in 2026 costs roughly 600 to 1,600 euros per m² of living area. For a property in poor condition that is gutted down to the shell, more than 2,000 euros per m² is possible too. For a single-family house of around 140 m² that works out to roughly 85,000 to 225,000 euros, and a true gut renovation can exceed that.

One thing first: this calculator produces estimates and cost ranges, not fixed prices and not a quote. What drives the cost is the year of construction, condition, fit-out level, region and the scope of the work. Budget an extra 15 to 20 percent buffer for the unforeseen, because hidden defects in older buildings often only show up once the construction site is open.

You enter the building type, year of construction, living area, condition and fit-out level, then pick the planned measures. Heating adds the planned heating system, the bathroom and windows add a count. Each measure is calculated from a reference value, either per m² of component area (roof, facade), per m² of living area (electrics, floors), per window or as a flat rate per heating system.

Condition, year of construction and fit-out act as multipliers on the range. For heating, the fit-out level deliberately has no effect, because the price of a new heating system barely depends on how high-end the bathroom tiling is. The result is a cost range from and to per measure, the total estimate and the value per m² of living area.

Year of construction: Older buildings carry more structural risk, such as contaminants, structural issues or heritage-protection requirements. That is why the multiplier rises with age.

Condition: Badly in need of renovation means more demolition and disposal, and therefore higher costs than a well-kept property.

Fit-out level: Basic, standard and premium mainly change the bathroom, floors and windows. The heating price stays untouched in the calculator, because it barely depends on the fit-out standard.

Region and market: The workload of local firms, material prices, scaffolding and site set-up land differently depending on location.

GEG retrofit obligations apply especially after a change of ownership, that is a purchase or inheritance, within two years of the land-register entry. Three obligations are central here.

§ 47 GEG: The top-floor ceiling, or alternatively the roof, must be insulated to a U-value of no more than 0.24 W/(m²K). For single- and two-family houses this is a retrofit obligation after a change of ownership.

§ 72 GEG: Constant-temperature boilers older than 30 years may not be kept in operation. Low-temperature and condensing boilers are exempt.

§ 71 GEG: When a new heating system is installed, the 65 percent renewable-energy obligation applies.

Anyone who has lived in a house with up to two flats themselves since 1 February 2002 is exempt from parts of the retrofit obligation. After a change of ownership, however, the obligation can apply. This is not legal advice: clarify the GEG obligations in your individual case with an energy advisor or specialist. Which obligations apply to you and what energy class your building has is shown by the energy efficiency quick check.

Building envelope (BEG individual measures, BAFA): For roof, facade, windows, top-floor ceiling and basement, you get 15 percent on up to 30,000 euros of eligible costs per residential unit and year without an individual renovation roadmap. With an individual renovation roadmap (iSFP) the figures rise to 20 percent and up to 60,000 euros per residential unit and year. The calculator shows the iSFP variant as the best case and caps the envelope total at 60,000 euros before funding.

Heating (KfW, programme 458): Only climate-friendly systems (heat pump, biomass, heat-network connection, hybrid) are eligible. There is 30 percent base funding, plus a 20 percent speed bonus for owner-occupiers (full in 2026, stepping down in later years), plus a 5 percent efficiency bonus, plus a 30 percent income bonus for a taxable household income up to 40,000 euros per year. In total the funding is capped at 70 percent, on eligible costs up to 30,000 euros for the first residential unit.

Put honestly: the 70 percent is the best case with the income bonus. For a typical household without it, heating funding is realistically closer to around 50 percent. That is exactly why the calculator shows both figures. Gas and oil boilers are not eligible via the KfW; here only the partial tradesperson bonus under § 35a EStG remains.

The order matters: you apply before commissioning the work, confirmed by a certified energy efficiency expert. The iSFP adds the 5 percentage-point bonus on the envelope. Which programmes fit your project you can check in the funding finder, and the savings potential in the energy efficiency quick check.

Owner-occupied property (§ 35c EStG): Energy measures are deductible at 20 percent over three years (7, 7 and 6 percent), up to 40,000 euros per property. The conditions are a building older than 10 years, a contractor certificate and measures completed by 31 December 2029. This cannot be combined with BEG or KfW for the same measure.

Tradesperson labour (§ 35a EStG): 20 percent of labour and travel costs, up to 1,200 euros per year. Only the labour portion is deductible, not the material.

Rented property: Maintenance expense is deductible immediately or spread over two to five years, while production costs run via depreciation (AfA). Watch the near-acquisition production costs under § 6 (1) no. 1a EStG: repair and modernisation expenditure within three years of the purchase that exceeds 15 percent (net of VAT) of the building acquisition costs becomes production costs and is only deductible via depreciation. This is not tax advice; consult a specialist in your individual case.

If your equity is not enough, you finance the renovation with a renovation loan or a modernisation loan. You plan the payment and remaining debt with the mortgage repayment calculator. Equity, funding and loan interact: the more funding you secure, the smaller the loan you need.

An energy renovation usually raises the value of the property too. How much is best put in context with a property valuation that takes the condition and the modernisation into account.

The calculator does not replace on-site measurement, a quote or professional planning. Real offers can differ considerably, so the rule is: obtain at least two to three quotes from specialist firms.

Hidden defects such as damp, contaminants or structural issues can blow the budget. They often only show up once the construction site is opened. A 15 to 20 percent buffer is therefore not a luxury but a must.