The specific time conversion from PDT to another time zone depends on the location. There is a three-hour time difference between PDT and EST, so 12 p.m. PDT is 3 p.m. EST. 12 p.m. PDT is 8 p.m. BST.
One needs to know details of a specific place--such as its latitude and longitude--in order to determine the actual time there. Sunset and sunrise times vary by location and determine the change in time zones. One can calculate the time in a different time zone if she knows how far behind or ahead the time zone is in reference to their own time zone.