This calendar lists opera (and opera-adjacent: operetta, zarzuela, vocal recitals, oratorios, choral works, etc.) performances.

There are two tabs: United States and Canada.

A similar (but much less comprehensive) European calendar can be seen here.

For many events, casts and other information (composer, etc.) are included to facilitate searches and statistics.

Given the large number of events, it is much more convenient to subscribe with your own calendar application.

You can use this link for the US events or this link for Canada.

For instance, in Google Calendar, on the left bar click the plus sign next to "Other calendars" and then "Add from URL".

You would then subscribe to the calendar and receive updates automatically.

Please let me know of any comments, omissions and corrections.