What is the building coefficient?
The building coefficient is a numerical parameter that regulates how many square metres can be built on a specific plot. Expressed as a decimal number (such as 0.6, 0.8, or 1.2), it means that the total sum of all buildable floor area cannot exceed that multiple of the plot size. It is defined nationally in the New Building Regulation (Law 4067/2012) and locally by municipal town plans and zoning decisions.
The building coefficient is fundamental to any construction project. Before purchasing a plot or beginning design, you must know your coefficient precisely so that your project complies with the law and avoids costly revisions or legal disputes.
How are buildable square metres calculated?
Calculating the total buildable area is straightforward and relies on a simple multiplication: plot area times the building coefficient.
Formula: Buildable m² = Plot area × Building coefficient
Example: If you own a 500 m² plot and your zone has a building coefficient of 0.8, your total buildable area is 500 × 0.8 = 400 m². This means the sum of all floor areas in your building cannot exceed 400 m².
Multi-storey application: If you build two storeys, each would be approximately 200 m². Three storeys would be roughly 133 m² per floor. The limit applies to the total across all floors, not to each floor individually (unless local rules specify otherwise).
What counts toward building coefficient and what does not?
Not all floor area counts equally toward the building coefficient. Some spaces are counted at reduced rates or not at all, depending on Greek regulations and local rules. As of the time of writing, these generally apply:
Fully counted:
- Enclosed main living or working spaces (living rooms, bedrooms, offices)
- Kitchens and dining areas
- Bathrooms and toilets
- Hallways and staircases
- Commercial and industrial workspaces
Partially counted or conditional:
- Basements (typically with a reduced coefficient, per regulation)
- Semi-enclosed or semi-open spaces (rules vary by municipality)
- Garages and parking areas (often counted at 0.35 or similar reduced rate)
- Auxiliary rooms (storage, service areas)
Not counted or minimally counted:
- Open balconies and terraces (typically excluded)
- Common areas in multi-unit buildings (usually not counted toward individual unit coefficient)
- Loggias and open galleries
- Technical infrastructure spaces (partially)
The exact rules vary by use type (residential, commercial, industrial) and local ordinances. Always verify the current rules with a structural engineer or your local planning authority before finalizing any design or submitting permits.
Building coefficient, coverage, and height: how they differ
The building coefficient, plot coverage, and building height are three separate parameters often confused. Each regulates a different aspect of construction:
Building coefficient (Syntelestis Domisis): The total buildable square metres across all storeys divided by plot area. It controls the density of the development. A high coefficient allows more total floor space; a low one restricts it.
Coverage: The percentage of ground area occupied by the building footprint when viewed from above (like an aerial photograph). A 50% coverage means the building footprint covers half the plot, with the other half remaining open. Coverage is independent of how many storeys you build.
Example: A 500 m² plot with coefficient 0.8 and 40% coverage means: 1) Total buildable m² = 400 m²; 2) Ground footprint = 200 m² (500 × 40%); 3) You can build two storeys of 200 m² each, or other combinations totalling 400 m².
Height: Simply the maximum vertical dimension the building can reach (e.g. 9 metres, 12 metres, etc.). Regulated separately and not directly linked to coefficient or coverage, though it does influence how many storeys fit within the height limit.
Where to find your building coefficient
Your zone's building coefficient is public information available from several sources:
1. e-Poleodomia (gis.epoleodomia.gov.gr): The Ministry of Environment's digital mapping platform lets you enter an address or postal code and instantly view the building coefficient and all zoning rules for that area. This is the fastest and most reliable source.
2. Property Registry (Ktimatologio.gr): The Greek national property database provides zoning maps and property records. While it does not directly show building coefficients, you can cross-reference zoning information to determine coefficients from municipal plans.
3. Local building authority or municipality: Your town's Building and Urban Planning Department (YDOMO) maintains detailed zoning documents and can provide coefficients directly. You can contact them by phone or visit in person.
4. Structural engineer: A local engineer familiar with your area can tell you immediately and help you understand what the coefficient means for your specific project goals.
When does the building coefficient change?
The building coefficient is stable as long as the town plan or zoning ordinance that defined it remains in effect. However, it can change under these circumstances:
1. Town plan revision: When a municipality updates or amends its town planning rules, coefficients for specific zones may be adjusted. These changes are published via Presidential Decree or municipal planning decisions.
2. National or EU legislation: Changes to national building law (such as amendments to the NOK) can affect zoning rules. However, such changes are rare and usually do not apply retroactively to already-approved projects.
3. Land use reclassification: If an area is reclassified from industrial to residential, or vice versa, the coefficient may be adjusted to match the new use category.
Why you need an engineer before buying a plot
Understanding your plot's building coefficient before purchase is critical to making the right investment. A large plot with a low coefficient may have little building potential, while a small plot with a high coefficient might be highly profitable. A structural engineer can:
- Calculate exactly how much you can legally build
- Flag any zoning complications or special conditions
- Alert you to possible changes in the town plan
- Guide you through proper procedures and optimisation strategies
Frequently asked questions
What is the building coefficient in simple terms?
The building coefficient is a number that tells you how many square metres you can build relative to your plot size. For example, if you own a 500 m² plot with a building coefficient of 0.8, you can build up to 400 m² total across all floors. It is set by Greek law (NOK) and varies by location and land use zone.
How is the building coefficient calculated?
The building coefficient is calculated by dividing total buildable square metres by plot area. If the result is 0.6, it means building volume cannot exceed 60% of your plot area relative to a 1:1 floor-to-area ratio. All enclosed and semi-enclosed floors count, while coverage and height are regulated separately by different rules.
Where can I find my plot's building coefficient?
You can find the building coefficient for your area through the e-Poleodomia platform (gis.epoleodomia.gov.gr), the Greek Property Registry (Ktimatologio), or your local building authority. In most cases, searching by postal code or municipality gives instant results showing all applicable zoning rules.
What is plot coverage and how does it differ?
Coverage is the percentage of ground area occupied by the building footprint (viewed from above). It differs from building coefficient. A plot might have a 0.8 coefficient (two floors of 400 m² each) and 50% coverage, meaning the building footprint covers only 50% of the ground while the other 50% remains open space.
What is the difference between building coefficient and coverage?
Building coefficient includes all square metres that can be built across all floors. Coverage is only the percentage of ground area shadowed by the building. You might have a 0.8 coefficient with 40% coverage, meaning restrictions on plot footprint size but freedom to add multiple storeys.
Do basements and semi-open areas count toward building coefficient?
As of the time of writing, basements and semi-open spaces generally count toward total buildable square metres, though the regulation has exceptions and sometimes applies reduced coefficients. We recommend verifying the exact provisions with a structural engineer before any planning, as rules vary by region and use type.
Sources: Law 4067/2012 NOK (kodiko.gr) · Hellenic Cadastre
Written and reviewed by Premier Construction's engineering team. Last updated: 24 July 2026. This article is general guidance and does not substitute for technical or legal advice on a specific property. Meet our team.