If your Google Form should stop collecting signups after 100 responses, do not rely on checking the response sheet manually. Set a response cap, prepare the closed-form message, and test the public form before launch.
For a simple event, class, RSVP, or volunteer form, the setup is usually this direct.
This form is now closed because we have reached 100 responses. Thank you for your interest.
Registration is full. To join the waitlist, please use this form: [waitlist link].
The event has reached capacity. Contact [email] if you need to update an existing RSVP.
This signup has reached its limit. Please contact the form owner before making plans.
Google Forms is not a strict reservation database. If several people already have the form open while the 100th response arrives, one or more late submissions may still race the closing rule.
Close the form after the configured number of submissions.
Show a clear message when the form is no longer accepting responses.
Notify the form owner when the control point is reached.
Combine response limits with scheduled close times and choice-level quotas when needed.