Floor area ratio - all information

A woman sits at a desk with a laptop, construction plans and a yellow hard hat.

The floor area ratio (GFZ) is a key factor in construction planning. It determines the permitted ratio of the floor area of all full storeys to the total area of your property. Specified in the development plans of your city or municipality, this figure forms an essential basis for the granting of building permits. So if you want to find out how intensively you are allowed to build on your property, you should look at the floor area ratio. Only then can a building project be planned efficiently and with legal certainty.

Definition and regulation: Why does the floor area ratio exist?
Calculation of floor area and floor area ratio (GFZ)
The value-relevant floor area ratio (WGFZ)
What is the difference between GFZ and GRZ?
Influence of the floor area ratio on the valuation of properties
The role of a real estate agent with regard to the calculation of GFZ and GRZ
Talk to the experts at Isar Estate about the GFZ calculation now
FAQ on the floor area ratio

Definition and regulation: Why does the floor area ratio exist?

The number of storeys is defined in Section 20 of the German Land Use Ordinance (BauNVO). As a yardstick, it regulates the sum of the floor areas of all full storeys of a building in relation to the size of a building plot. This regulation regulates building density in both urban and rural areas. Maximum values prevent overbuilding and promote environmentally friendly and socially just construction. The floor area is usually determined by the responsible building authorities or town planning offices as part of the urban land-use planning and in accordance with local regulations.

What is the GFZ value of a municipality based on?

Depending on the location and type of area, the floor area ratio varies considerably in some cases. In rural areas and smaller settlements, it is usually below 1, reflecting a lower density of development. Residential areas, especially those in inner-city environments, on the other hand, show GFZ values of around 1 or even higher, which indicates denser development.

In specific urban zones such as commercial areas or core areas, the number of storeys can be significantly higher. This variation reflects the different planning objectives and requirements for land and environmental use, from the preservation of rural characteristics to the support of urban densification and economic activities in core and commercial areas.

Calculation of the floor area and floor area ratio

The floor area (GF) is the sum of all usable floor areas of a building. It generally includes all areas that are covered and used. This includes residential, commercial and retail areas. Special rules apply, among other things:

Attic floors
Cellar
Technical floors
Underground garages

It is important to know that only full storeys are included in the calculation of the floor area. The formula for their calculation is

Floor area (GF) = GFZ x plot area (G)

Assuming that the floor area ratio of your plot is set at 0.7, this means that the sum of the areas of your full storeys may not exceed 70 percent of the plot area. For a plot of 1000 square meters, a GFZ of 0.7 therefore allows the construction of buildings with a maximum cumulative floor area of 700 square meters.

However, if you know the floor area and the plot area, you can use the following calculation to determine the GFZ:

GFZ = Floor area (GF) / plot area (G)

How is a full storey defined?

The exact definition of a full storey is determined by the respective state building regulations of the individual federal states. It is therefore possible for an area to be considered a full storey in Bavaria, whereas it is not used to calculate the storey area in Saxony. However, the plot area (G) always refers to the total area of the respective building plot.

Attic storey, balcony or underground garage as special cases in the GFZ calculation

In practice, there are several methods for calculating the floor area. This is because buildings have architectural features that make it necessary to include various usable areas such as attics, balconies or underground garages. For example, according to the applicable regulations, attics are either fully or only partially included in the floor area, which can make a significant difference.

Underground garages and technical storeys can also be taken into account under certain conditions. Furthermore, local regulations allow cities and municipalities to define their own criteria for dealing with the number of storeys.

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The value-relevant floor area ratio (WGFZ)

The question of the so-called value-relevant floor area ratio (WGFZ) often arises in the same breath. This is an extension of the GFZ, which does not only include full storeys in the calculation. Other areas, such as those just mentioned, are taken into account for this calculation, even if they are not full storeys.

Calculating the WGFZ - example regulations of the City of Munich

For example, the expert committee of the City of Munich also takes into account the following when calculating the WGFZ , in deviation from the Building Utilization Ordinance:

Areas of sales rooms and recreation rooms on other storeys that are not considered full storeys
associated corridors, sanitary facilities, stairwells and elevator rooms
Half of attic areas with a clear height of at least one and less than two meters

The latter also applies if they are full storeys under building law. Drive-throughs, integrated underground parking garage exits and arcades are not included in the floor area ratio, which is particularly important for property developers in Munich.

What is the difference between GFZ and GRZ?

While the floor area ratio determines the relationship between the sum of all floor areas and the size of the plot, the ground area ratio (GRZ) determines what percentage of a plot may be built on. With a GRZ of 0.4, for example, 40 percent of the plot area may be built on. Bear this factor in mind if you are selling a plot of land in Munich.

Some facts about the floor area ratio

The GRZ is used in various contexts under building law. When examining building applications, it is used alongside the floor area ratio to assess whether the planned building project complies with local regulations.

It is also used to limit the sealing of soil surfaces. This is particularly important in areas where drainage and surface water management play a role.

The floor area ratio is also important for the promotion of green spaces and open spaces: in residential areas, a low GRZ can help to leave sufficient space for private gardens, playgrounds and recreational areas.

In this way, the floor area ratio controls the spread of development in a similar way to the floor area ratio - but in a horizontal direction. Soil sealing is effectively limited.

Architect and draughtsman discuss floor plan with pencils and ruler on a table.

Influence of the floor area ratio on the valuation of properties

Now that you know what the floor area ratio is used for, our real estate experts would like to explain why it is important for your property valuation in Munich. It is a key indicator that exerts a considerable influence.

Significance for property developers and investors

The floor area ratio is of particular interest to investors and property developers, as it is a measure of the economic utilization potential of a property. A high GFZ enables a more intensive use of the property, which can lead to increased rental income or higher sales proceeds in real estate sales for developers. Particularly in areas with strong demand for residential or commercial space, a high floor area ratio can significantly increase the property value.

The role of a real estate agent with regard to the calculation of GFZ and GRZ

Our real estate agents play an important role in dealing with the floor area ratio, as they act as an interface between owners, buyers, investors and authorities. We inform you about applicable regulations in the Munich area, analyze development plans and help you to realistically assess the potential of a property.

Our specialist knowledge of the impact of local building regulations on development projects makes a decisive contribution to minimizing your investment risk and making sustainable long-term decisions. The same applies, for example, to house sales in Munich.

Typical tasks of a real estate agent:

Examination of the permissible GFZ and GRZ as well as other building regulations
Assessment of the planned use (e.g. residential or commercial building)
Calculation of possible floor area to determine the realistic property value
Support with preliminary building inquiries or coordination on possible deviations.
Identification of opportunities for redensification or expansion of existing properties, taking into account the floor area ratio

As competent real estate agents, we combine legal understanding with market knowledge and thus create the basis for sound investment decisions - especially in sensitive urban regions such as Munich. We would be happy to discuss with you the extent to which the number of storeys and floor area have an impact on your real estate project.

Black and white portrait of Christian Dürr, founder of Isar Estate.

Talk to the experts at Isar Estate about the GFZ calculation now

Would you like to know more about the floor area ratio? Then the Isar Estate team will be happy to assist you. Our real estate agents in Munich and beyond will advise you on optimal marketing and letting. We listen to you carefully and give you individual recommendations for action.

Dipl.-Kfm. Christian Dürr
Founder Isar Estate

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FAQ on the floor area ratio

Where can I find the floor area ratio of my property?

The respective floor area ratio is specified in the development plan of your municipality or town. This can usually be viewed at the building authority or online. For existing properties, the land use plan also provides information. Our real estate agents will be happy to help you interpret the values correctly.

How is the floor area ratio calculated?

The GFZ is calculated as the sum of all floor areas of the buildings on the plot divided by the plot area. All full storeys are decisive. Attic floors only count if they are considered full living space. The final calculation is based on the German Land Use Ordinance (BauNVO).

What significance does the GFZ have when selling a house?

The floor area ratio is an important factor for buyers, as it determines the possible building density. A high value means more usable space and therefore often a higher property value. Real estate agents therefore take the floor area ratio into account in the valuation in order to realistically assess potential.

Can the floor area ratio be changed?

A change is only possible by adapting the development plan and this is usually a complex procedure. In exceptional cases, an exemption can be applied for, for example if it is in the interests of urban development. Building authorities also examine each application individually, so specialist advice is essential here.

Why is the calculation of the GFZ important for investors and planners?

This is because it largely determines how profitable a construction project can be. It shows how much residential or commercial space can be realized on a plot of land. Investors, architects and estate agents therefore use the floor area ratio to precisely calculate the exact space utilization as well as construction costs and potential income.

Disclaimer

Despite careful research and checking of the sources, the author assumes no liability for the accuracy and completeness of the information presented. In case of unclear legal and tax questions, it is advisable to consult a lawyer and/or tax advisor for clarification.

Author: Dipl.-Kfm. Christian Dürr