Is there any way that I can determine the exact bytes (size) that a table has used so far instead of looking at the bytes columns of the dba_segments view and also without caculating the average row length? The bytes column from dba_segments only gives me the size(in bytes) based on the initial_extent(and or next_extent) specified during the table creation.

I would like to determine the actual size(in bytes) of the table not based on the initial and the next extents specified during table creation