Blog · Event access control
How many scanners does my event need at the door?
The number that matters isn't how many people are coming — it's how many want to get in at the same time. Here's the math, with measured figures rather than guesses.
The question always lands a few days before the event: "we're expecting 800 people — how many phones scanning tickets will be enough?" The honest answer is that 800 is not the number that decides.
The peak decides, not the total
A conference where 800 attendees trickle in over two hours looks nothing like a concert where 800 pour in within twenty minutes. The first needs far less than people assume; the second, quite a bit more.
The calculation that actually works for QR check-in at the door:
- How many people you need through the door in the peak minute.
- One scanner running on an ordinary phone sustains 15 to 25 scans per minute, allowing for the attendee who has to dig the code out of a bag.
- Divide the first by the second and add one.
For 800 people arriving over twenty minutes: 40 per minute at the calm end, more than double that if they bunch up. Two scanners is cutting it close; three is comfortable.
The server is almost never the problem
It's the question we get asked most and the one that matters least. In our measurements, the platform sustains more than 200 scans per second with a hundred scanners working simultaneously across several events. That's over 12,000 scans per minute.
No physical gate anywhere moves 12,000 people per minute. The bottleneck is the turnstile and the corridor, not the technology. Size your entry for the space and the number of hands, not for the server.
What actually jams
In order of what we have genuinely seen fail:
A single entry point. Four scanners at the same door produce the same queue as one. Spread arrivals across entrances, even if you have to signpost them.
The attendee's phone. A large share of the time per person goes on unlocking the screen and hunting for the email. A reminder the evening before, with the QR code one tap away, saves more seconds than any server-side optimization ever will.
Network coverage. A venue with thick walls or a basement level can leave you without data exactly when everyone shows up.
And if the network drops
This is the scenario to have planned in advance, not improvised at the door.
The QRACCESS app works offline: it validates tickets against a local copy and queues the scans. When the signal comes back, they sync up. Check-in doesn't stop because the venue Wi-Fi does. See how the app behaves online and offline for the details.
The trade-off: without a connection, two scanners can't see each other, so the same code could get through two different doors. If that matters to you — and with paid admission it does — split the venue into zones so that each QR code is only valid at one of them.
Quick reference
| People in the peak minute | Scanners |
|---|---|
| Up to 20 | 2 |
| 20 to 40 | 3 |
| 40 to 70 | 4 |
| More than 70 | Split across several gates |
And always add one more than the math says. The phone that dies halfway through admission is a classic, and preventing it is far cheaper than fixing it with a queue already forming. Setting up extra scanner users takes a minute, and the mobile app page covers what each device needs.
Related reading: static or dynamic QR codes for tickets — which should you use?