Actual space used per table

Hi all,
I am using ave_row_len as calculated by analyze ; <ave_row_len> * <number of rows > .
 How much overhead should I add ? My tests show that 2000 bytes per block as unaccounted for.   

4251 rows = 65536 bytes

ave_row_len = 10

4251 * 10 = 42510

Data is in 8 blocks.

2878.25 is overhead per block: 820 bytes is PCTFREE ( 10 % of block size ).

Where is the rest ?

Please advise.

  Thanks, Ranko.

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