use strict;
use File::Find::Rule;

my $dir = "c:/temp/test";

my @results = File::Find::Rule->file->in( $dir );
my $totalsize = 0;
foreach my $result ( @results ) {
	$totalsize += (stat($result))[7];
}
my $mbtotalsize = $totalsize /1024 / 1024;

print "$dir=$mbtotalsize MB\n";