In depth
QR codes on slides: time to scan
Sizes for projectors and screens, how long to keep the slide up and where to send the audience.
Size on screen
Projectors reduce contrast and blur fine modules. Give the code at least a quarter of the slide height on a plain light background.
| Room | Code height on screen |
|---|---|
| Meeting room up to 20 people | 15–20% of slide height |
| Conference hall up to 150 | 25–30% of slide height |
| Large stage | 35% or more, or codes on side screens |
How long to show it
People need time to take out the phone and open the camera. Keep the code slide up for at least 20–30 seconds and say what is inside: “Slides and my contacts are here.” The final slide during Q&A works best.
- One page with slides, links from the talk and contacts.
- A cloud folder shared by link.
- A feedback or next-event sign-up form.
Never place the code over a photo: the busy background kills contrast on a projector. Put it on a white panel — the studio shows whether it still reads.