Here's how to find contacts that aren't in a specific group:
- Go to the main Contact list by selecting "Contacts" in the navigation bar.
- Select "Add a filter" in the "Sort and filter" section on the left.
- In the dialog that appears, select "Group" from the dropdown.
- In the dropdown that appears below that, choose "Show contacts that are NOT in the following group(s)."
- Tick off the desired group name(s), and apply the filter to see contacts that are not in the selected group(s).
- Want to see contacts that aren't in any group instead? Learn how to filter to contacts that aren't in any group here.