The Cathedral and the Castle have different ticket offices. Tickets for the Cathedral can be purchased only in the ticket office directly opposite the Cathedral entrance. While entrance to the actual cathedral itself is free you will need a ticket to enter the adjoining Royal Crypts and Sigismund Bell tower. A single ticket covers these as well as the Cathedral Museum. Audioguides are recommended to make the most of the experience, and can be rented here for 7/5zł (in Polish, English, German, Russian, Italian, Spanish, Czech, French and Hungarian).
Open 09:00 - 16:30. Sun 12:30 - 16:30.
Tickets covering the Cathedral Museum, Royal Crypts and Sigismund Bell cost 12/7zł. Note that the Cathedral Museum is closed Sun, but your ticket is valid to visit another day.