memory_limit Setting?

Hi everyone, I¹m trying to upload a 25MB file via PHP and I¹m setting the memory limit way high so I don¹t get a fatal error from php (the error is below). What I find really odd about this is that the error message says that PHP tried to allocate almost 54MB. First question is why is PHP allocating so much memory when I¹m only uploading a 25MB file? Second question is why is PHP failing when obviously the memory limit is set to just over 100MB? (I¹m using PHP 5.1.2 Apache 2.0.55 and using an .htaccess file to change the PHP settings on the fly.) Fatal error: Allowed memory size of 104857600 bytes exhausted (tried to allocate 53764163 bytes) in /path/to/php/file on line 942 .htaccess settings below: php_value memory_limit 100M php_value post_max_size 30M php_value upload_max_filesize 30M php_value max_execution_time 300 php_value max_input_time 300 php_value display_errors On