Set Max signups per user on the event's Event Details tab. 1 means one slot each — the right setting for parent-teacher conferences or anything appointment-shaped. 0, the default, means unlimited.
Once someone reaches the limit, further signups on that event are refused with a message telling them how many they may take. Cancelled signups don't count against it: giving a spot back frees the allowance again.
Two things to know about how a "person" is identified:
- A logged-in user is matched by their account, so a second email address does not buy a second allowance.
- A guest can only be matched by the email address they type. Someone determined to work around the limit could use another address. Turn on Require users to be logged in to sign up on the same tab when the limit needs to be airtight.
The limit counts signups on that event only — someone can still take a slot on a different event.
For a hard cap on total attendance rather than per person, use slot capacity instead; that is what it's for. See Adding Time Slots.
