use Devel::Size qw(size total_size); $a{1} = undef; $b{1} = 0; $c{1} = 1; $d{1} = 10; $e{1} = 'abcd'; print "$_: ".(total_size( \%{$_} ) - size( \%{$_} ))."\n" for a..e; __END__ a: 12 b: 16 c: 16 d: 16 e: 29