Geschossflächenziffer

Geschossflächenziffer, often abbreviated as GFZ, is a key term in German zoning and land-use planning. It translates to Floor Area Ratio or Floor Space Index in English. The GFZ is a regulatory figure that determines the maximum permissible gross floor area (Geschossfläche) that can be built on a given plot of land relative to the size of the plot itself.

To calculate the GFZ, one divides the total sum of all gross floor areas of all building storeys by the area of the plot. For example, if a plot of land is 1,000 square meters and the GFZ is 0.8, the maximum permissible gross floor area for buildings on that plot is 800 square meters. This figure applies to the sum of all floors, including basements and attics, if they are usable.

The GFZ serves as a crucial tool for urban planners to control building density and ensure adequate open spaces. By setting limits on the buildable floor area, it influences the overall character of a neighborhood, prevents overcrowding, and helps manage infrastructure demands such as traffic, utilities, and public services. Different GFZ values are typically stipulated in local development plans (Bebauungspläne) depending on the zoning category, desired density, and urban design objectives.