This feature is available to Pro and Enterprise plans

You definitely can!

1. Click the Settings button to the left of your event's homepage to go to the Event Information page.

2. To the right, you can now adjust how many RSVPs you want to allow. Enter how many RSVPs you like, then Save.

Adding +1s

Are you allowing your attendees to bring +1s? If so, you're in luck. +1 guests will be counted towards the total capacity, along with your original invitees. This means that you will have an accurate display of exactly how many guests plan to attend your event. 

If the capacity only allows for one more guest, and your invitee tries to register with a +1, they will see an error letting them know that there is only one more seat left for the event. All error messages can be further customized via: How do I edit the error messages on my form?