Built Area vs Usable Area: How to Actually Read the Square Meters in a Foreign Listing (2026)

Published on: June 20, 2026

You find two apartments in two countries. Both are advertised at 90 square meters. Both are priced the same. One has noticeably more living space than the other, and it is not the one you would guess. The reason is that the number 90 does not mean the same thing in Madrid, Paris, Rome, and Tokyo.

Square meters look like the most objective figure in a listing. In reality, every country measures floor area differently, and the gap between what is advertised and what you can actually live in can run from 10 to 35 percent. If you compare prices on the headline area without understanding what it includes, you are comparing numbers that are not the same number. This guide explains how floor area is measured across the major markets and how to read it like a local.

Quick answer: Most listings quote a built, gross, or commercial area that includes wall thickness, a share of common areas, and balconies, often 10 to 35 percent more than the usable floor inside your own walls. Spain shows metros construidos and metros utiles, France certifies the loi Carrez area, Italy quotes the generous superficie commerciale, and Japan often prices per tsubo (about 3.3 square meters). Always compare usable area to usable area, and recalculate price per square meter on the space you can actually live in.

Why the headline number is almost always generous

Across most of the world, the area in a listing is measured to include things you cannot live on: the thickness of the walls, a share of the building's common areas, balconies, and sometimes cellars and parking counted at a reduced rate. This is the built or gross or commercial area, and it is larger, often considerably larger, than the actual interior space your furniture occupies.

The smaller, more honest number is the usable area: the floor you can walk on inside your own walls. Sellers and agents naturally prefer to advertise the larger figure, because a higher area lowers the apparent price per square meter and makes the property look like better value. None of this is necessarily dishonest. It is simply local convention, and the convention is different in each country.

Spain: construidos versus utiles

In Spain, two figures appear constantly, and the difference between them is the first thing a local buyer checks.

Metros construidos, the built area, includes the interior space, the thickness of the perimeter and interior walls, and a proportional share of the building's common areas such as the lobby, stairwells, and corridors. Metros utiles, the usable area, is the interior floor you can actually use, measured inside the walls.

The built figure is typically 10 to 20 percent larger than the usable figure, and in buildings with generous common areas it can be more. A flat advertised at 90 metros construidos might offer around 75 metros utiles of real living space. When you compare Spanish properties, compare utiles to utiles, and always ask for both numbers if only one is shown.

France: the loi Carrez

France solved part of this problem with the law, which is why French listings for apartments quote a specific, legally defined figure.

For properties held in co-ownership, the loi Carrez requires the seller to state the certified private floor area. This area excludes walls, stairs, and any space with a ceiling height below 1.8 meters, and it excludes balconies, terraces, cellars, parking, and any lot smaller than 8 square meters. The number is measured and certified, and if the actual area turns out to be more than 5 percent smaller than stated, the buyer has a legal remedy on the price.

The loi Carrez area is therefore close to true usable space and is more reliable than a casual built figure. Be aware of a related but different measure, the surface habitable under the loi Boutin, used for rentals, which is defined slightly differently. For a purchase, the loi Carrez figure is the one that matters.

Italy: superficie commerciale

Italy takes the opposite approach to France and quotes one of the most generous figures in Europe.

The standard Italian measure is the superficie commerciale, the commercial area, and it is what listings and price-per-square-meter calculations are based on. It includes the interior space, the walls, and a percentage of balconies, terraces, cellars, and parking, each weighted by a coefficient. A balcony might count at 25 to 35 percent of its area, a cellar at a similar reduced rate, and so on.

The result is that an Italian apartment advertised at 100 square meters commerciale may contain only 75 to 80 square meters of actual internal walkable space, the superficie calpestabile. When you evaluate an Italian property, ask for the calpestabile, the walkable area, alongside the commerciale, and recalculate the real price per square meter on the space you will actually use.

Japan: tsubo and the metric trap

Japan adds a second layer of complexity, because it often does not use square meters at all in conversation and marketing.

The traditional unit is the tsubo, equal to roughly 3.3 square meters, historically about the size of two tatami mats. Listings and price quotes are frequently given per tsubo, so a price that looks low per unit is actually per 3.3 square meters, not per single square meter. To compare with a European listing, convert: multiply the tsubo figure by about 3.3 to get square meters. Japanese listings also typically separate the balcony area, which is treated as common property, and distinguish the registered exclusive area from the gross figure. Always confirm whether a quoted area and price are per tsubo or per square meter before you compare anything.

The rest of the world, briefly

The same pattern repeats with local names. In India, listings have historically quoted super built-up area, which can inflate the real space by 25 to 40 percent by loading in common areas, although the RERA framework now requires the carpet area, the true internal space, to be disclosed. In Brazil, area util is the usable area and area total includes common space and parking. In the United States, area is in square feet, usually measured to the exterior walls as gross living area, and basements and garages are often excluded, which is its own source of confusion. Wherever you buy, there is a generous number and an honest number, and they have different local names.

Why this quietly distorts every price comparison

Price per square meter is the universal yardstick of international real estate, and it only works if the square meters mean the same thing on both sides of the comparison.

Consider the same apartment priced at 450,000 euros. On a 100 square meter commercial area it looks like 4,500 euros per square meter. On the 78 square meter walkable area it really contains, the true cost of usable space is closer to 5,770 euros per square meter. Two listings at the same headline price per square meter can hide a 20 percent difference in real living space. This is not a rounding error. It is often the difference between a fair price and an expensive one, and it compounds the professional disagreements we describe in the international property valuation gap.

How to protect yourself

Always ask which area a listing quotes, by name, in the local convention. Ask specifically for the usable, walkable, or carpet figure: utiles in Spain, calpestabile in Italy, carpet area in India. In France, rely on the certified loi Carrez area for apartments. Convert units deliberately, especially tsubo in Japan, before comparing anything. For a significant purchase, have the space measured independently or surveyed, rather than trusting the brochure, which matters even more when you buy remotely and never see the rooms. Finally, recalculate the price per square meter on the usable area, not the built or commercial one, and compare only like with like. An inflated area is also one of the softer tactics in the international real estate scam atlas, so treat a number you cannot verify as a question, not a fact.

The square meter is the most quoted and least understood number in a foreign listing. Once you know which one you are looking at, you stop comparing apples with floor plans, and you start seeing what you are really paying for.

Frequently asked questions

What is the difference between built area and usable area?
Built area (gross or commercial) includes the thickness of the walls, a share of the building's common areas, and often balconies and storage counted at a reduced rate. Usable area is only the floor you can walk on inside your own walls. The built figure is usually 10 to 35 percent larger, which is why it makes price per square meter look lower.

What do construidos and utiles mean in a Spanish listing?
Metros construidos is the built area, including walls and a share of common space. Metros utiles is the interior usable floor. The built figure is typically 10 to 20 percent larger, so a 90 metros construidos flat might offer around 75 metros utiles. Compare utiles to utiles across Spanish listings.

Why is a Japanese price per tsubo so confusing?
A tsubo is about 3.3 square meters, so a price quoted per tsubo is per 3.3 square meters, not per single square meter. To compare with a European listing, multiply the tsubo figure by roughly 3.3 to convert to square meters first.

A note from JanusHermes

We wrote this because price per square meter is the number cross-border buyers lean on most, and it only works once you know which area it is built on. But JanusHermes is a cross-border real estate platform, not a surveyor or valuer, so treat this as orientation, not advice. Explore listings and country-level intelligence across 50+ markets on JanusHermes.

Disclaimer. This article is provided for general information only and does not constitute valuation, legal, or investment advice, nor does it create any professional or advisory relationship. Measurement standards are set by local law and custom and can be revised, and the figures here are illustrative. Always confirm which area a listing quotes and obtain the legally certified figure before relying on a price per square meter. JanusHermes is a property information and listing platform and accepts no liability for any action taken in reliance on this content.

A note on the numbers: where no source is named, the market figures in this article (prices, yields, costs) are indicative estimates compiled from publicly available market data and industry reporting at the time of writing. Markets move and rules change, so treat them as a starting point and verify current figures with official sources before acting on them.