QR codes for webinar signup

Two moments, two codes

Webinar registration has exactly two moments where a QR code earns its place:

1. Promotion: flyers, posters, conference handouts, booth panels pointing at the registration page. Ordinary print rules apply: 3 cm at arm's length, 10–30 cm on panels, a stated benefit beside the code.
2. The closing slide of a live talk: the highest-intent audience you will ever face, already convinced by forty minutes of you, needing only a frictionless way to get the next thing. This is the moment worth engineering, and it has its own physics.

Tag them separately (utm_content=flyer versus utm_content=talk-slide), so you learn which moment fills the webinar; the UTM how-to has conventions.

The closing-slide physics

A projected slide is a screen read from much further than a poster, and the 10:1 distance rule is unforgiving about it. A typical projection is 2.5–3 m wide; a mid-sized room seats people 10–15 m from it. The back row therefore needs a code 1–1.5 m wide on the projection, a third to half the slide. The discreet corner code that looks tasteful in the deck is unscannable beyond the front rows; the same arithmetic governs codes on TV screens.

So design the slide around the code: the code enormous, one line of benefit ("Seats for the deep-dive, 30 seconds to register"), and a short typeable URL beneath it. Nothing else. Every additional element shrinks the one thing the slide exists to do.

Two behaviours work in your favour:

• Audiences photograph slides. Phones can scan a code from a photo later, and in a photo of the whole room, your code is a small region of the frame, which is precisely why oversizing matters. Big codes survive being photographed; small ones become smudges.
• A slide has no time limit. Unlike video, you control the projector: leave the registration slide up through the entire Q&A. Minutes of passive exposure beat any ten-second end card ever aired.

From signup to attendance: the calendar step

Webinar economics die between registration and the live date, people sign up sincerely and forget completely. The single highest-leverage fix is getting the event into the registrant's calendar at the moment of signup:

• Have the confirmation page offer the event as a calendar entry: a calendar QR code on the thank-you screen works when the signup happened on a laptop and the phone should hold the reminder; the calendar generator builds the event payload, which the phone saves offline, no server involved.
• Send the standard confirmation email with an attached invite as well; the two channels are complementary, not redundant.

A calendar entry is a reminder you did not have to earn twice. Reminder emails still help, but they compete with the inbox; the calendar alarm does not.

Before the talk

Load your own deck, walk to the actual back row, and scan the slide. If it fails from there, the code is too small: fix it before the audience proves it for you. And decode the artwork with the validator whenever the deck has been through a designer: recolouring and compression have quietly killed more slide codes than projectors ever did.

FAQ

How big should a QR code be on a presentation slide?

Size for the back row: at 10–15 m from a 2.5–3 m projection, the 10:1 rule demands a code 1–1.5 m wide on screen, a third to half of the slide. Make the code the slide's main element, not a corner ornament.

Should I leave the QR code up during Q&A?

Yes: it is your biggest advantage over video. A slide has no duration limit, so minutes of passive exposure let everyone scan at leisure, including people photographing the screen to scan later from the photo.

How do I stop webinar registrants forgetting to attend?

Put the event in their calendar at signup: a calendar-file link or QR on the confirmation page, plus an invite attached to the confirmation email. A calendar alarm fires regardless of inbox noise, which reminder emails cannot promise.

What should the webinar registration form ask for?

As little as possible: email, perhaps name. The scanner is standing in a conference room or reading a flyer; every extra field costs registrations, and everything else can be collected inside the confirmation flow.