Free tool
Buildability and site coverage calculator
With four figures from the planning sheet you can see how many square metres of floor area fit on your plot, how much ground the house or warehouse can cover and how much land stays open. Everything is calculated in your browser: nothing is sent.
How we calculate
- Floor area by buildability: plot area × ratio. With 600 m² and 0.5 m²/m² you get 300 m² of floor area.
- Maximum footprint: plot area × coverage. With 600 m² and 30 %, the building’s ground floor cannot exceed 180 m².
- Floor area by coverage and storeys: maximum footprint × number of storeys. The buildable floor area is the smaller of the two: planning rules require both limits at once.
- Open land: what is left of the plot outside the maximum footprint, for garden, patio, access and parking.
What the calculator does not do
It does not take into account the shape of the plot, the setbacks from boundaries and the street, or the height in metres, which can leave less room than the coverage suggests. Nor does it know what your municipal plan counts (basements, porches, covered terraces). Your plot’s figures are in the planning certificate (cédula urbanística) from the town hall and in the Mapa urbanístic de Catalunya; the professional who signs the project confirms them.
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Frequently asked questions
What is the buildability ratio?
The square metres of floor area you can build for each square metre of plot (m²/m², in Spanish m²t/m²s). With 0.4, a 500 m² plot allows 200 m² of floor area, adding up all storeys.
How much can I build on a 1,000 m² plot?
It depends on the ratio and coverage of your zone. With 0.3 it would be 300 m² of floor area; if coverage is 20 %, the footprint cannot exceed 200 m², so you would need two storeys to use it all.
Where do I find my plot’s buildability?
In your municipality’s planning rules (in Catalonia, the POUM or subsidiary rules), in the planning certificate the town hall issues and, for a quick look, in the Mapa urbanístic de Catalunya.
Do a pool or a porch count as floor area?
Each plan decides: the zone rules say what counts towards floor area and coverage. Check the rules or ask the town hall before drawing.