You can calculate the size of the controlfile from V$CONTROLFILE_RECORD_SECTION. The size of each section is RECORD_SIZE * RECORDS_TOTAL rounded up to a whole number of blocks. The controlfile block size is the same as the database block size. You then need to double that size, because all data in the controlfile is stored in duplicate. This is needed to recover in case the instance or system crashes in the middle of a controlfile transaction. Finally, you also need to allow 1 block for the file header. There is a script called controlfile_size.sql on the Ixora web site that will do this all for you.

Is there a view somewhere that will tell me the size of the controlfiles? I can find database files; I can find redo log files; but I cannot find control files, and I have users asking about "total space consumption on the XXX server". Currently I use 10M as an estimated size, thinking that guessing higher is safer.