use set_time_limit(0); function at the start of the php page.
In the case of uplodaing large size file also timeout error will come. In this case you can edit the .htaccess file in the root folder. you can add the following values inside the htaccess file.
php_value max_input_time 200
php_value post_max_size 20M
php_value max_execution_time 200
php_value upload_max_filesize 15M