How Switzerland measures a home — three official answers to the same rooms

The constitutive deed of a Swiss condominium states the spatial delimitation and each unit's share of the property's value, as a fraction over a common denominator. No square-metre figure appears there, and none appears in the main-book extract a land registry issues either. Anyone wanting the living area of their flat therefore gets no further through the main book — only through the question of which rule was used to measure.

Source: Swiss Civil Code art. 712e (Fedlex) · Guide: the value quota in Swiss condominium ownership

At what room height a floor area starts counting at all is not uniformly regulated in Switzerland. The federal rule names 150 cm — that is the WBS criterion K15, quoted verbatim above. Of the prevailing calculation models, architektvergleich.ch writes, in German: «Denn dieser Punkt ist nicht einheitlich geregelt, sodass Abweichungen sowohl nach oben als auch nach unten hin möglich sind» — this point is not uniformly regulated, so deviations upwards and downwards are both possible. And SIA 416 names no height at all for its Hauptnutzfläche HNF. Comparing two area figures for the same flat may therefore mean comparing two different height thresholds — and neither is wrong, as long as it says which one applies.

Source: Net living area — living-area calculation models (architektvergleich.ch, in German)

Raiffeisen, which offers its members IAZI's online property valuation, names a 1.2 m threshold for that tool and excludes storage rooms (as at 01.07.2025). That is a bank's statement about somebody else's model. IAZI itself publishes no area definition — no height threshold and no include/exclude list, in any of its languages. A column headed IAZI would therefore rest entirely on a third party's sentence, and no rule on this page is one its named source does not publish itself. So the model that helps decide a mortgage is precisely the one with no column here — and what it computes with stays a question for whoever runs it.

Source: Market value of a property (raiffeisen.ch, 01.07.2025) · Glossary: hedonic estimate · Guide: the hedonic estimate explained

The WBS 2015 glossary defines the quantity itself: «Zur Nettowohnfläche zählen sämtliche begeh- und belegbaren Bodenflächen innerhalb der Wohnung ab einer Raumhöhe von 150 cm» — every walkable, usable floor area inside the dwelling from a room height of 150 cm. That is not merely a measuring instruction but a membership definition with three conditions — walkable and usable, inside the dwelling, from 150 cm — and it settles every row those three conditions reach. Which zones lie inside the dwelling the brochure says itself: circulation, cooking, dining, sanitary, storage and outdoor zones are listed under the heading «Nutzungsbereiche in der Wohnung», usage zones in the dwelling. The storage room and the corridor therefore count; that a corridor is usable too the glossary states expressly under storage — cupboard modules may be «in der Erschliessungszone … untergebracht», housed in the circulation zone. The cellar and the balcony do not count, and not because the German word for the outdoor zone contains «outside»: the brochure lists it among the zones in the dwelling. What decides it is that the WBS gives each of them its own criterion with its own square-metre measure — K25 «Private Abstellräume ausserhalb der Wohnung», private storage rooms outside the dwelling, for the cellar, and K23 «Privater Aussenbereich» for the balcony, loggia and terrace, where «Balkone, Terrassen, Loggien, Zwischenzonen und Gärten» are counted in full. Exactly one cell stays open: where a winter garden does not lie inside the heated insulation perimeter the source leaves it to the assessor — «Liegen Zwischenzonen nicht innerhalb des Dämmperimeters, können diese als Aussenbereich angerechnet werden», they may be counted as outdoor space instead. A «may» is not ours to settle for you.

Source: WBS 2015, glossary (bwo.admin.ch)

The Swiss building and dwelling register holds a «dwelling area» attribute for every flat; it sums rooms, kitchens, bathrooms, lavatories, storage rooms, corridors and verandas. Two of its exclusions are routinely read as deductions and are not — they stop the same area being counted twice. «Individual habitable rooms (e.g. attic rooms)» are, in the same catalogue, rooms that «are not part of a dwelling»; they are registered as a dwelling of their own, with their own dwelling area. «Separate habitable rooms» is the attribute GAZZI, the number of habitable rooms «not part of a dwelling», and it says expressly that rooms inside a dwelling do not count as separate habitable rooms. Of the attic space inside your dwelling, only the exclusion of non-habitable cellar and attic rooms is left. A converted, habitable attic room is a room of the dwelling and counts in full — at any room height. That this is deliberate the same catalogue shows elsewhere: for the energy reference area GEBF it records that «areas with a clear height of less than 1.0 m are excluded». Where it means a height threshold it writes one down; for the dwelling area there is none. The same paragraph also says what the figure is allowed to be: «If it cannot be determined exactly, the surface area is estimated by multiplying the length of the dwelling by its width. Enter the gross floor area if this information is available.» The catalogue names the building permit as its data source — the plan, not a survey after construction; the value is captured by the municipal building offices under a reporting obligation. The only federal quality requirement is a plausibility range: under 5 m², over 400 m² per room and over 2200 m² are inadmissible — that last threshold was raised from 1700 m² on 17.11.2025. The rules therefore describe what should be captured; what a stored value actually is cannot be read back from them. It corresponds to the register entry and is not verified on site — a register statement, not a measurement.

Source: Building register catalogue 4.3, «WAREA» (housing-stat.ch) · Glossary: GWR · Guide: a register value is not the truth

In its 2003 edition the norm is titled «Flächen und Volumen von Gebäuden», areas and volumes of buildings; the addition «und Anlagen» belongs to the title of the withdrawn 1993 edition. It divides a building's areas: the floor area GF into net floor area NGF and construction area KF, the NGF into usable area NF, circulation area VF and services area FF, and the NF into Hauptnutzfläche HNF and Nebennutzfläche NNF. The column follows from that, row by row. The norm names no room height anywhere — the word «Höhe» does not occur once in the reproduction; an attic room counts towards HNF whatever its height, and the 150 cm threshold comes not from here but from the Federal Housing Office's WBS. Storage rooms, attic and cellar rooms, laundries, garages and shelters the norm lists expressly as Nebennutzfläche — so they are not HNF. Walls, columns and parapets are construction area and lie outside the net floor area. An open balcony is not a floor area at all: only the «allseitig umschlossene und überdeckte Grundrissfläche», the plan area enclosed on every side and covered, counts as one. Its circulation area the norm defines functionally: «Die Verkehrsfläche VF ist jener Teil der Nettogeschossfläche NGF, welcher ausschliesslich deren Erschliessung dient» — the part of the net floor area that serves exclusively to give access. An interior maisonette stair meets that without qualification — nothing else happens on a stair — so it is circulation area and not HNF. For the corridor it is precisely not clear cut: the functional definition could claim it, but the example list names only corridors «ausserhalb der Wohnung», outside the dwelling, and is prefaced «z. B.», for example, so it does not close the case. That one row therefore reads «not stated», and the page says why. A glazed winter garden, by contrast, is enclosed on every side and covered, so it is floor area, and it appears nowhere among the Nebennutzflächen — it belongs to HNF, heated or not. What comes out at the end is a usable area: it leaves out the storage room you use every day and takes in the 1.3 m corner under the roof slope where nobody can stand. A living area it is not.

Source: SIA 416 «Flächen und Volumen von Gebäuden», 2003 edition (SIA shop)

Several Swiss market sources converge on a rule that appears in none of the three primary sources for the area calculation: «Die Räume müssen beheizbar und ganzjährig bewohnbar sein», writes neho.ch, and a winter garden counts towards the living area when heated and habitable all year; acheteur.ch asks the same under the headings «Beheizbarkeit» and «Bewohnbarkeit». That is widespread convention, not a rule — Switzerland has a de-facto living-area convention with no official author. For the area itself none of the three sources sets a heating condition; the WBS attaches heating to something else — «Zimmer sind natürlich belichtet, belüftet und beheizt» — and so to the room count, not to the square metres. We name the market rule because you will meet it in practice, and we keep it outside the three source columns, where it does not belong.

Source: Calculating living area (neho.ch)

None of the three sources states a measuring convention — wall to wall, from the finished surface, or clear internal dimension. And none states a rounding rule or a tolerance. Those two therefore carry the «Could not resolve» state — not a number we picked. The enclosed, glazed balcony used to stand here as a third; it no longer belongs, because the register excludes expressly only «open balconies», which answers the question for its column. When two figures for the same flat differ by a few square metres, it is often down to the two that remain.

Source: Calculating living area (acheteur.ch)

Where a document, a listing or a form says only «living area» and nothing else, we read it as a net living area (Nettowohnfläche). That is an alpflo house convention, adopted so that we speak the market's language — and expressly not a claim that the net living area is a standard. Nor is it a computation: how any given area figure was produced, we still cannot say.

Source: Calculating living area (neho.ch)

Take the figure that matches your question: the register area when you are checking a register statement; the WBS area when a housing statistic or a subsidy refers to it; the Hauptnutzfläche HNF when a building project or an area survey computes under SIA 416. Ask, in the listing and at the viewing, which method was used — that is the only detail that truly resolves the divergence, and nobody can derive it for you.

Source: Net living area, WBS 2015 (bwo.admin.ch) · Calculator: buildable floor area

No. There are several published rules with different thresholds. Which one applies depends on who produced the figure.

Differently by source, and the two federal sources are opposed here: the WBS 2015 measures from a room height of 150 cm, while the building and dwelling register names no room height at all for its dwelling area — a habitable attic room counts there in full at any height. SIA 416 names no height for the Hauptnutzfläche HNF either. Below 150 cm the area therefore falls away only under the WBS. Of the prevailing calculation models, architektvergleich.ch writes that this point is «not uniformly regulated».

For both federal sources, yes. The register lists «storerooms» expressly in its sum, and the WBS counts one through its definition: a Reduit is walkable, usable floor area inside the dwelling, and the brochure lists the storage zone among the usage zones in the dwelling. Only SIA 416 lists storage rooms expressly as Nebennutzfläche NNF — so they are not Hauptnutzfläche HNF.

No. It reproduces published rules on your own figures. Nothing is measured, and no bank is bound by this result.