What is the size of an Oracle table? A very rough approximation is to multiply the number of rows with the average row length in bytes. Fortunately, Oracle directly provide you with such information. Take this query:
select table_name , num_rows , avg_row_len ,to_char((num_rows * avg_row_len)/1000000,'9999999D999','NLS_NUMERIC_CHARACTERS=''. ''') as sizeMB , blocks from dba_tab_statistics where owner like 'ST%';
This can be verified in SQL Developer when you investigate the tablespaces:
