Oracle Table and Database Size

To obtain the table size on an Oracle database, the following script can be used:

SELECT lower(table_name) AS tableName
    ,blocks*8/1024 AS Mbytes
FROM all_tables
WHERE owner = USER

Performing the sum of the sizes of all tables allow us to get an estimate of the database size:

SELECT sum(blocks*8/1024) AS TotalMbytes
FROM all_tables
WHERE owner = USER;

The previous script may not be accurate because it actually gets the sum of the size of the tables, which can be simply viewed as the data size, since a database is more than just data on tables.