Why two Czech adverts can quote different areas for the same flat

Two adverts for the same flat can quote two areas, and both can be honest. One lists 54 square metres, the other 49. The gap is not a lie, but a choice of what to count. The loggia may have been added at half its size, or at full, or left out. The cellar may be inside the figure or separate. The thickness of the walls may be inside or outside the line. For a buyer who thinks in price per square metre, a few square metres is a few per cent of the price.

Which area?

Czech practice uses several measures, and each has a respectable purpose. They answer different questions.

Podlahová plocha (floor area) is the area of the floors of the rooms of the flat measured within the finished walls. It is the closest to what a person standing in the flat would call its size.

Užitná plocha (usable area) is a technical term from building standards for the area that can be used, normally floor area of rooms and ancillary spaces within the flat, excluding structures such as walls and, in many methods, outdoor spaces. In Czech adverts it is a common label, and it is used loosely, sometimes as if it meant the same as floor area.

Obytná plocha (living area) counts only the habitable rooms, such as the living room and bedrooms, and leaves out the kitchen (if separate), the bathroom, the hall and the storage. It is smaller than floor area, and it is why a flat can have a much smaller living area than floor area.

Zastavěná plocha (built-up area) is something else altogether: the footprint of a building on its plot. It appears in house listings and development documents, not in flat adverts.

Celková plocha (total area) is the label sellers use when they have added outdoor and ancillary spaces, such as balcony, loggia, terrace and cellar, to the interior area. It is the largest figure, and it is the one that can mislead.

What the standards say, and what they do not

Several documents define area for specific uses. Czech technical standards (ČSN) set vocabulary and measuring methods for buildings; see building standards and technical norms. Valuation rules, used by experts who value property for banks and courts, have their own definitions. The cadastre and the declaration of the owner record the area of a unit for ownership purposes. Each is correct for its own job.

What is missing, as far as the published rules show, is one obligatory method that every private advert must follow (as of 2026; check ÚNMZ, the Ministry for Regional Development and ČÚZK). Technical standards are generally voluntary unless a law or contract makes them binding, and they are sold by the standards body, not published openly. The practical result is that the seller or agent chooses the label and the method, and the reader has to ask.

Where the area is written down

For a flat in a building divided into units, the declaration of the owner (prohlášení vlastníka) is the key document. It describes each unit and normally gives its floor area, together with the unit's share of the common parts. Our guide to the cadastre of real estate explains how the declaration and the extract fit together, and the article on reading an extract shows what the extract contains.

The area in the declaration is also the basis for the unit's share in the common parts and, by default, for voting power in the owners' association (see how owners vote). A buyer who finds a large difference between the declared area and the advertised one has a reason to ask why.

A hypothetical example

To show how the figure moves, take a hypothetical flat. The rooms, kitchen, bathroom and hall add up to 52 square metres of floor area. It has a loggia of 4 square metres and a cellar of 3 square metres.

• Floor area: 52 square metres.
• With the loggia counted at half: 54 square metres.
• With the loggia and cellar both counted in full: 59 square metres.

Three honest adverts could quote three figures. If the asking price is divided by each figure, the price per square metre differs by more than a tenth between the lowest and the highest. Nothing is false, but a comparison of two flats quoted by different methods is meaningless.

Special cases

Attic flats (podkroví) are the usual trouble. Under sloping ceilings the floor exists but is not very usable, and methods differ on whether low areas are counted in full, reduced or excluded. Ask how the figure was calculated.

Outdoor spaces are counted in some methods with a reduction factor, since a loggia is not equal to a room. The factor is the choice of the method, not a legal constant.

Wall thickness matters in older brick buildings, where walls can be very thick. A measurement from the outside of the wall gives a higher number than one taken inside.

New builds present areas in the price list, usually per unit with the floor area and the outdoor spaces shown apart. The developer's sales documents, the contract and the declaration should agree. If they do not, the discrepancy belongs in writing before signing. The purchase sequence is described in our guide to buying an apartment in Czechia.

Reading a developer's price list

In a new building the sales documents often show several numbers for each unit, and it helps to know which is which. A typical price list gives the interior floor area, then the area of the balcony, loggia or terrace, then any cellar or parking space, and sometimes a total. The contract should repeat the same figures. If it gives only a total, ask for the breakdown in writing, because the total hides how much of it is outdoor space. A flat with a large terrace and a modest interior can show the same total as a flat with a bigger interior and no terrace, and the two do not live alike.

The declaration of the owner for the new building will normally be filed before the first sale. Compare its figure for your unit with the price list. A small difference can come from rounding or from the final survey after completion. A large one needs an explanation before you sign.

Why it matters for value

Price per square metre is the main way the market compares flats, in adverts, price indices and valuations. Statistics built on adverts inherit the same inconsistency. For a seller, the same logic works in reverse: if a flat's area is stated higher than its neighbours' by a different method, a buyer will notice.

Frequently asked questions

Is there one official way to measure a flat in Czechia?

Not for private adverts, as far as the published rules show. Standards and valuation rules define area for their own purposes, and the declaration of the owner records the unit's area for ownership. Check the source document for the method (as of 2026; check ČÚZK and the Ministry for Regional Development).

Does the cadastre show the area of my flat?

The declaration of the owner, which is filed in the cadastre, normally gives each unit's floor area and share. Check the documents for your own unit.

Should balconies be included in the price per square metre?

It depends on the method used, so compare like with like. Ask for the interior area and the outdoor areas separately.

What if the flat is smaller than the contract says?

The contract and the circumstances decide what remedies exist. Take legal advice from a Czech lawyer at the time, and keep the advert, the plan and the declaration.

Before you compare two flats, put both on one line of a notebook: floor area, outdoor areas and the method, with the document it came from.

This is a general explainer, not legal or tax advice.