Buildable area calculator
Find out how many square metres you can build on your plot. Enter the plot area, the plot ratio and the coverage from your local plan and get the maximum buildable floor area instantly.
What plot ratio is and how to calculate it
The plot ratio (also called floor area ratio or buildable area) is the maximum floor area you may build on a plot. It is given as a coefficient in buildable m² per m² of land. Multiply the plot area by that coefficient to get the maximum buildable floor area: if your plot is 800 m² and the plot ratio is 0.6, you may build up to 800 × 0.6 = 480 m².
The plot ratio is not the whole story. Planning rules also set the maximum site coverage (the share of the plot the building footprint may occupy), the height or number of floors, the setbacks (minimum distances to boundaries and roads) and the permitted uses. Coverage limits how far you spread horizontally; height, how far you go vertically. With both figures this calculator shows the maximum footprint and how many floors you would need to use up the buildable area.
All of these parameters are defined by each town’s local development plan (PGOU) and the planning record of each plot. Along the Costa del Sol they vary widely between Marbella, Estepona, Benahavís or Mijas, and even between areas of the same town. That is why this tool is indicative: to know exactly what you can build you need the planning certificate and a feasibility study.
Frequently asked questions
How do I find the plot ratio of my plot?
It appears in the planning record or certificate issued by the town hall, derived from the local plan. An architect can also check it from the cadastral reference and the land classification.
What is the difference between plot ratio and coverage?
Plot ratio is the total floor area you can build across all storeys. Coverage is the percentage of the plot the building may sit on at ground level. You can have a high plot ratio but low coverage — in that case you build upwards.
Does the buildable area include basements, porches or a pool?
It depends on the local plan. Basements, terraces, porches and pools often count only partially or not at all towards the plot ratio, but each municipality has its own rules, so it should be checked case by case.
Is this calculation legally binding?
No. It is an indicative estimate to give you a quick idea. The actual buildable area depends on your plot’s planning record and the interpretation of the local plan, which must be verified by an architect.
Can you tell me what I can build on my plot?
Yes. At Serrano Font we carry out planning feasibility studies in Marbella and across the Costa del Sol: we analyse the local plan, the plot ratio, the uses and the conditions of your plot before designing. Get in touch.
Want to know exactly what you can build?
We prepare the planning feasibility study for your plot in Marbella and the Costa del Sol.
Request your study