Sena

Original research, October 2026

Four in ten registrants did not come. Most went quiet first.

We messaged every FOST London registrant with a phone number on WhatsApp before the doors opened. 39% never picked up a badge. Three quarters of them had read our message, or received it, and never answered.

39%

of 1,411 registrants never picked up a badge

19%

no-shows among registrants who replied before the event

43%

no-shows among registrants who got the message and stayed silent

74%

of all no-shows came from the silent group

What one WhatsApp message tells you about attendance

Registrants who replied missed the event at less than half the rate of everyone else.

No-show rate, by what each registrant did with the message

Replied before the event
18.8%

165 registrants

Read it, never replied
42.8%

663 registrants

Received it, never opened it
45.2%

279 registrants

Number not on WhatsApp
45.2%

199 registrants

No confirmed message
33.3%

69 registrants

A read message without an answer made no difference. Silent and unreachable registrants stayed away at the same rate.

Source: FOST London 2026

Swipe the table to see every column

Group Registrants No-shows No-show rate
Replied before the event 165 31 18.8%
Read it, never replied 663 284 42.8%
Received it, never opened it 279 126 45.2%
Number not on WhatsApp 199 90 45.2%
No confirmed message 69 23 33.3%
All pre-registered 1,411 555 39.3%

A reply predicts attendance. It does not cause it.

People who plan to come are the ones who answer, and two numbers show it.

Length did not matter: registrants who sent one or two messages missed the event at 20%, and those who sent five or more at 18%.

Registrants who read the message and stayed quiet missed the event at 43%. Those that the message did not reach missed it at 45%.

The silent registrants are your list of likely no-shows, days before the event.

We have not yet tested whether the message itself changes who comes. When we do, the result goes on this page.

What a quiet registrant costs you

A no-show is a seat you already paid for. Your caterer counted it and your sponsors expected it. Someone on your waitlist wanted it.

At FOST London, 144 more people registered on the day. The people who wanted those empty seats were at the door.

A registration list cannot tell you which names will not come. Until the morning of the event, they all look the same.

What you can do with a list of likely no-shows

  • You know who is at risk, days out. The silent registrants were three quarters of the no-shows.
  • You hear who cannot come. Eight registrants told Sena that they cannot come, and seven of them did not come.
  • You ask the quiet ones on the morning. Do you still plan to come today? A yes is a confirmed seat. A no is a seat for your waitlist.
  • You reach the ones WhatsApp cannot. One registrant in six never got the message, and they missed the event at 43%. Email gets them the same assistant on the web.

What these numbers cannot tell you

We compared the FOST London badge list with who replied to Sena before the event.

  • This is one two-day tech conference in London, and your rate will be different. We do not publish an industry average, because we have not measured one.
  • Nothing here shows the message changed anyone's plans. It predicts attendance only.
  • Some groups are small, for example the eight who told Sena that they cannot come. Treat their rates as rough.
  • Some people turn read receipts off, so part of the "never opened" group did open the message.
  • The 144 people who registered on the day all came. We left them out, because they make the rate look better.
  • We sell this, so every figure carries its count for you to check.

No registrant's name, contact details or employer appears on this page. Citation and reuse are welcome under CC BY 4.0.

Frequently asked questions

How do you know which registrants will not show up?

Ask them something before the event and watch who answers. At FOST London 2026, registrants who replied to the event's WhatsApp message before doors opened had an 18.8% no-show rate. Registrants who got the message and stayed silent had 43.5%. The silent group made up 74% of all no-shows.

What was the no-show rate at FOST London 2026?

39.3%. 555 of 1,411 pre-registered attendees never picked up a badge. Another 144 people registered on the day and all of them attended. They are not in the rate.

Does a WhatsApp message to attendees reduce no-shows?

Not proven. Registrants who replied came far more often, but people who plan to attend are the ones who reply. Registrants who got the message and did not answer missed the event at the same rate as registrants who did not get it. Nobody has tested that yet.

What can an organizer do about registrants who never reply?

Treat them as the at-risk list. At FOST London they were three quarters of the no-shows. On the morning of the event, ask them if they still plan to come. Give the seats of anyone who says no to the waitlist.

What about registrants who are not on WhatsApp?

At FOST London, 199 of 1,411 registrants had a number that was not on WhatsApp, and 35 had no phone at all. They missed the event at 43%, the same as the silent group. They need a second channel, for example an email with a link to the same assistant on the web.

Keep reading

Know who will come before the doors open

We will send you the anonymized sponsor report from one of our events: 1,306 registrants, start to finish.

A real, anonymized sponsor report from a live event. No newsletter, no sequence.