QR codes on slides, screens and video

Screens are a harder surface than paper

A code on a slide is read from across a room, at an angle, often over a projector's washed-out contrast, by someone who has to get their phone out first. Compared with a printed page held in the hand, almost every variable is worse. Size accordingly: a slide code should be a substantial element, not a footnote in the corner.

Leave it up for long enough

People need time to notice the code, retrieve a phone, unlock it, open the camera and aim. Fifteen seconds is a realistic minimum; thirty is better. In video, a code that appears for five seconds is decoration. If the format cannot spare the time, use a spoken short link instead, which the viewer can act on later.

Projector contrast is the usual failure

Rooms are rarely dark, projectors are rarely calibrated, and a mid-grey code on an off-white slide that looks fine on a laptop can be nearly invisible on the wall. Use pure black on pure white for slide codes, and check it on the actual projector during the technical run-through.

In video, watch for compression

Streaming compression is unkind to high-frequency detail, which is exactly what a QR code is. A small code in a fast-moving frame can be reduced to mush at lower bitrates. Keep it large, keep it static on screen, and place it against a flat background so the encoder has less to fight with.

Say the link out loud as well

Viewers watching on a phone cannot scan the screen they are watching, which is a large share of your audience on social video. A memorable spoken short link is the only thing that works for them. Show both, and give them different content parameters so you can see which the audience used.

Pick a destination worth the interruption

Someone scanning a code during a talk is stepping away from your talk. The destination should be something they cannot get later — the slides, a resource list, a discount — not your home page. Set it up so the page works without any further navigation.

Give each deck and each screening its own link

Conference talk, webinar, sales deck and recorded version all deserve separate links. Talks get reused for years, and knowing which venue produced scans is the only way to judge whether speaking at an event was worthwhile.