The density values (1–5) on the playing cards show how intensively an urban building block is used. Here we explain the key metrics behind them and how the levels are derived: in Residential/Work/Education/Retail they are based on values per hectare (RU/ha, Jobs/ha, Edu/ha, SF/ha), in the Mixed Use category the level represents the number of combined uses. Below you will also find the two planning metrics GRZ and GFZ. Further terms can be found in the Glossary.
Formula: RU/ha = number of residential units ÷ plot area in ha
Basic idea: If the number of residential units is known, you calculate directly. If not, we estimate it from the building floor area (GFA).
The number of residential units per hectare (RU/ha) measures housing density. It varies greatly between loosely developed single-family home areas and compact urban quarters:
(1) Very low density (< 20 RU/ha): Corresponds to sparsely populated peripheral areas with predominantly single-family homes or village structures.
(2) Low density (20–40 RU/ha): Typical of suburban residential quarters with terraced houses or mixtures of single-family and small multi-family homes.
(3) Medium density (40–70 RU/ha): Corresponds to common multi-storey residential quarters in German cities. Many post-war and new development areas reach values in this range.
(4) High density (≈ 70–150 RU/ha): Characteristic of Gründerzeit (late 19th century) perimeter block development or dense urban quarters.
(5) Very high density (> 150 RU/ha): Exceptional cases with extremely compact residential development such as inner-city high-rise projects.
Formula: Jobs/ha = Number of Jobs ÷ site area in ha
Basic idea: If jobs are known, you calculate directly. If not, we estimate them from the floor area (GFA) and a reference value.
Jobs per hectare (Jobs/ha) show how many jobs are concentrated in an area. The values vary greatly depending on the type of use and building form:
(1) Very low (< 50 Jobs/ha): Small office buildings or commercial buildings in sprawling industrial parks or peripheral areas.
(2) Low (50–200 Jobs/ha): Smaller office buildings or commercial buildings in commercial zones or peripheral locations.
(3) Medium (200–400 Jobs/ha): Medium-sized office buildings and commercial use units in urban areas with higher building density.
(4) High (400–800 Jobs/ha): More densely built office towers and medium-sized commercial parks in urban centres.
(5) Very high (> 800 Jobs/ha): Very compact and multi-storey office buildings with maximum site utilisation.
Formula: Edu/ha = Number of Learners ÷ site area in ha
Basic idea: If the number of learners/persons in care is known, you calculate directly. If not, we estimate them from the floor area (GFA) and a reference value.
Learners per hectare counts all persons who use educational offerings in an area (from nursery children to university students):
(1) Very low (< 200 Edu/ha): Small educational institutions such as individual primary schools or small nurseries in rural contexts.
(2) Low (200–400 Edu/ha): Medium-sized educational institutions such as secondary schools or grammar schools in urbanised districts.
(3) Medium (400–600 Edu/ha): Larger schools or universities with a higher number of pupils or students in urban neighbourhoods.
(4) High (600–800 Edu/ha): Larger educational facilities such as university complexes in highly dense urban areas.
(5) Very high (> 800 Edu/ha): Very compact and multi-storey educational institutions with maximum utilisation.
Formula: SF/ha = Sales floor area in m² ÷ Plot area in ha
Basic idea: If the sales floor area is known, you calculate directly. If not, we estimate it from the gross floor area (GFA).
The sales floor density measures the retail floor area (m² of sales floor area) per hectare:
(1) Very low (< 2,000 m²/ha): Single-storey buildings with a high proportion of parking spaces such as supermarkets.
(2) Low (2,000–4,000 m²/ha): Small to medium retail floor areas in neighbourhood centres.
(3) Medium (4,000–6,000 m²/ha): Shopping centres with higher floor counts but large parking areas.
(4) High (6,000–10,000 m²/ha): District centres and city centres with multi-storey shops.
(5) Very high (> 10,000 m²/ha): Prime city centre locations with maximum utilisation, up to 15,000 m²/ha in top shopping locations.
Formula: GRZ = (Building footprint + ancillary structures) ÷ Plot area
The Site Coverage Ratio indicates what proportion of a plot may be built upon. A GRZ of 0.4 means: on a 1,000 m² plot, a maximum of 400 m² of ground area may be occupied by buildings and ancillary structures.
What counts towards the GRZ? In addition to the building footprint, ancillary structures are also included: garages, parking spaces, driveways, terraces and other paved surfaces (pursuant to BauNVO §19). Important: Ancillary structures may exceed the GRZ by up to 50%, but may not exceed a total of 0.8 (§19 para. 4 BauNVO).
(1) Very low (0.1–0.2): Villa districts with large gardens and loose development.
(2) Low (0.2–0.4): Typical single-family home areas with front gardens and setback zones.
(3) Medium (0.4–0.6): Multi-storey residential buildings with green spaces between the buildings.
(4) High (0.6–0.8): Inner-city development, perimeter block development with little open space.
(5) Very high (0.8–1.0): Core areas with maximum plot utilisation.
Note: The GRZ says nothing about height – a single-storey building with a GRZ of 0.8 has the same footprint as a high-rise with a GRZ of 0.8.
Formula: GFZ = Sum of all above-ground floor areas ÷ site area
The floor area ratio indicates how much floor area may be built in relation to the site area. A GFZ of 1.2 means: on a 1,000 m² site, a total of 1,200 m² of floor area may be created (e.g. 3 storeys of 400 m² each). Note: Not all areas count towards the GFZ – pursuant to §20 BauNVO, basement storeys, garages below ground level, and certain ancillary facilities are among those not taken into account.
(1) Very low (0.2–0.4): Loose development, single-storey buildings with large open spaces.
(2) Low (0.4–0.8): Residential areas with 2–3 storey buildings.
(3) Medium (0.8–1.6): Urban residential areas with 4–6 storeys.
(4) High (1.6–2.4): Mixed-use areas and commercial centres with taller buildings.
(5) Very high (2.4+): Core areas and high-rise locations with maximum utilisation.
Note: GRZ and GFZ together determine the building form – a low GRZ with a high GFZ results in a high-rise, a high GRZ with a low GFZ results in low-rise development.