Google Calendar is an effective tool for organizing your life and getting small groups of people on the same page about upcoming events. If you're trying to put together a large gathering, though, it can be a mess. Google is adding some new features to Calendar to make organizing an event with large groups just a little less stressful.
The large group features apply only to events with 200 or more guests. If you're inviting people via a mailing list, Calendar will be smart enough to automatically invite new group members even after your event has been created. Likewise, those who leave the mailing list will be removed from the event. The mailing list management also works with recurring events.
You also won't need to rely upon the Calendar interface to keep track of who's attending large events when these changes go into effect. When you hit 200 guests, Google Calendar makes a Google Sheets export option available. From there, you can easily see who's responded to the invitation and what they said.
Both new features will roll out to users within the next few days. Be aware; you may need to create new events for the group features to begin working.
- G Suite blog