Event parking spaces calculator

The number of spaces comes from a formula with six variables: Spaces = (attendees × % by car ÷ people per car ÷ turnover + staff) × (1 + margin). First you get the audience cars, then you add staff cars and finally a reserve. The result is rounded up to whole spaces. Each variable has a different data source.

The calculator starts with these example values, which are not data from your event: 20,000 people at the peak, 55% by car, 2 people per car, turnover 1, 300 staff spaces, a 10% margin, 3% accessible spaces and 25 m² per space. Replace them with your own.

1. 1

   People on site at the busiest moment

   These are the people inside at the same time at the peak, not total tickets sold. Take it from the licensed capacity, from gate scans by time slot in previous editions or from the programme (a multi-day festival does not peak like a sports final).

2. 2

   Share arriving by car

   It includes drivers and passengers. It often varies a lot from one event to another. To measure it you can use ticket postcodes, a follow-up survey, volunteer counts at the entrances or parking and coach sales data. The survey template includes the questions you need.

3. 3

   People per car

   This is average occupancy: how many people travel in each car, driver included. Measure it with the survey or by counting at the car park entrance. The calculator does not accept less than 1. If you have no data yet, use a prudent value and check the reference table below.

4. 4

   Times each space is used (turnover)

   It is 1 if cars stay for the whole event, as at a festival. It is more than 1 if people come and go during the day and the same space is used several times (the calculator does not accept less than 1). Work it out from the event schedule and the length of stay in previous editions.

5. 5

   Spaces for staff, artists and suppliers

   They are added separately because they do not follow the audience's modal split. Ask production and whoever manages accreditations, and check whether they need separate areas.

6. 6

   Safety margin

   It covers surprises, blocked spaces, poor ground layout or worse occupancy than expected. There is no universal percentage: raise it if the ground is uneven, if rain is likely or if your starting data are estimates.

The share arriving by car and people per car are the two parameters that move the result most, because the formula combines them directly: the number of cars rises with the modal split and falls with occupancy. Going from 2 to 3 people per car, everything else equal, cuts audience cars by a third.

These are the official or published occupancy references you can use until you have your own data. None of them measures your event.

The sensitivity table in the calculator works as an argument in itself: it recalculates the spaces, the difference and the area for 1.5, 2, 2.5, 3, 3.5 and 4 people per car, with everything else equal.

A full space, including aisles and manoeuvring, takes between 20 and 25 m² according to the municipal ordinances we checked, and the calculator uses 25 m² by default. These are usual calculation rules in Spanish planning regulations, not rules for temporary event car parks.

Two variables concentrate the effect: fewer people arriving by car, and more people in each car. Turnover also reduces the spaces if the same space can be used several times, and staff and margin can be adjusted but usually weigh less. The onboard:earth guide lists concrete measures that act on the first two.

The calculator gives how many spaces you need as a total quantity, not how people get in and out. Before closing a design, complete the analysis with the points below.

• Entry and exit flows. It does not calculate how many cars per hour the access roads can take or how long the car park takes to empty. A car park with enough spaces can still block the road if entry is slow.
• Zoning. It does not split the spaces between audience, staff, artists, suppliers, coaches and pick-up areas.
• Accessibility. The calculator reserves a percentage of the total spaces as accessible (3% by default). It is indicative: check the regulation that applies to you for the exact minimum.
• Other vehicles. It does not include motorbikes, bicycles, coaches, caravans or emergency vehicles, which need their own space.
• Local regulation. It does not replace what the council, the regional government or the landowner require.
• Starting data. If the share by car or occupancy are estimates, the result is an estimate too. Check it against a survey after the edition.

Every extra person per car reduces the number of spaces you need, and to raise occupancy we recommend VIB3S, a carpooling platform for events: attendees share a car with other people going to the same event, the app is free (iOS and Android) and the driver splits the real cost of the trip with them, meaning fuel and tolls. It complements public transport and shuttles.

For you, VIB3S builds your event's community inside the app and gives you a web widget that plugs into your website, ticketing or emails with one line of code; on VIB3S's side it is ready in under 24 hours. Afterwards you see where your audience comes from, arrival and departure time slots, average occupancy per vehicle and cars avoided, data you can feed back into this calculator next time.