Timed entry slots with capacity limits spread an event’s attendees across time windows with limited space: each person picks a slot when they register, the system closes the slot when it fills, and the door checks that every QR comes in at its assigned time. It’s the tool for events where the space handles a fixed number of people per hour and a mass arrival would ruin the experience. Set up well, it eliminates lines; set up badly, it doubles them.
The problem time slots solve
Picture a brand activation with an immersive experience that lasts 20 minutes and takes 30 people at a time. Real capacity: 90 people per hour. Expected audience for the day: 2,000. If you leave entry open, by 11 a.m. you have 400 people on the sidewalk, a three-hour line and angry people leaving without getting in. The experience may be spectacular; the operation sank it.
Time slots flip the logic: instead of managing the line once it exists, you distribute demand before it arrives. Every attendee knows when to show up, the flow stays steady all day and capacity is fully used, with no peaks or valleys.
Typical cases where slots are the right answer:
- Immersive experiences and activations with small capacity against large demand.
- Showrooms, test drives and demos with personal attention.
- Service days (paperwork, pet neutering, public assistance) where each person takes a fixed amount of time.
- Guided tours inside a larger event.
- Events with strict capacity rules set by the local permit.
And the case where they don’t fit: if your venue comfortably holds the whole audience at once and the experience is free-flowing, don’t force slots. They add friction to registration and work at the door without solving any real problem.
How to size the slots without fooling yourself
The most common mistake is sizing slots on the space’s theoretical capacity instead of the operation’s real capacity. A serious calculation has three steps.
1. Real capacity per hour. It’s not how many people physically fit in the space: it’s how many people the experience can process per hour while keeping its quality. That includes entry time, the experience itself, exit and the reset between groups (cleaning, restocking, staff changeover). That reset, which looks like 2 minutes on paper, usually runs 5 to 8 on the ground.
2. Operating margin. Subtract 10% to 15% from the real capacity. That cushion absorbs delays, groups that run over, a piece of equipment that fails. A slot system sized at 100% falls behind by the third hour and drags the delay through the rest of the day.
3. Overbooking for no-shows. With free slots, some people don’t turn up: depending on the type of event, between 20% and 40%. If you don’t overbook, the experience runs half empty; if you overbook too much, you create a line exactly where you promised there wouldn’t be one. Overbooking is calibrated with the event’s own no-show rate: start conservative and adjust slot by slot with the live dashboard data.
An example with numbers
| Variable | Value |
|---|---|
| Experience capacity | 30 people every 20 minutes |
| Theoretical capacity per hour | 90 people |
| Operating margin (12%) | 79 effective people per hour |
| Slots offered | 3 per hour, capacity 26 |
| Overbooking for no-shows (25%) | published capacity: 32 per slot |
| 8-hour day | 768 published places, about 630 actual attendees |
With that picture you learn something more important than the slot size: if you expect 2,000 people, one day isn’t enough, and you found out on the spreadsheet and not on the sidewalk.
Door rules: where time slots live or die
A slot system without clear door rules is a promise that breaks at the entrance. Three definitions need to be written down before the event:
- Grace period: how many minutes late someone can arrive and still be accepted in their slot. Usually 10 to 15 minutes; after that, they get rebooked.
- Rebooking: whoever missed their slot goes to the next one with free capacity, no arguments and no exceptions for insisting. If the system shows the slots with space in real time, the conversation lasts 10 seconds.
- Early arrivals: whoever arrives before their slot waits, or takes a free place if there is one. They never displace someone who came on time.
The key is that these rules aren’t managed by staff memory: the system manages them. When the reader scans the QR, it has to say whether that person belongs to this slot and, if not, what option to offer. That validation follows the same logic as the event’s general access control, with the time dimension added.
One more infrastructure point: slots depend on the door validating against the database in real time, and venues don’t always come through on connectivity. The system has to keep validating if the WiFi drops, a scenario we cover in detail in access control without internet.
Communication with the attendee: half the system
The best slot engine fails if the attendee doesn’t understand what they booked. The minimum communication that works:
- On booking: immediate confirmation with date, time, address and the QR. In the same message, the grace period rule in one line.
- The day before: a reminder with a visible option to cancel or change slots. Every timely cancellation is a place that goes back on offer by itself.
- Two hours before: a last reminder, ideally through a more immediate channel than email.
- On site: signage that separates the line for the current slot from the rebooking line, so nobody waits in a queue that isn’t theirs.
The cancel option deserves emphasis. It seems counterintuitive to make dropping out easy, but every person who cancels in advance is a no-show that turns into a real place for someone else. Systems that hide cancellation don’t get fewer drop-outs: they get more empty seats.
The data you walk away with
A well-instrumented slot system leaves information that open entry never gives you: demand by time window, real no-show rates by day and by hour, actual time per group, and which windows to reinforce or drop in the next edition. If the event repeats, that data is worth as much as the operation itself: the second edition gets sized with evidence, not intuition.
At SOMOS DER we develop our own technology for registration, timed entry slots with capacity limits and access control, and we run it on the ground with our own team. If your event has more demand than instant capacity and you want to spread it out without lines or improvisation, request a quote telling us the capacity of your experience and the audience you expect.