What is the default Maximum file upload size and how to change it?

By default Maximum file upload size is 128MB.

php_value upload_max_filesize 128M
php_value post_max_size 128M

If you want to change the default Maximum file upload size from 128MB to 1GB, then it can be done by changing in the these files..

1.) In .htaccess file (Apache + mod_php) add the following two lines to a .htaccess in the installed directory:

php_value upload_max_filesize 1G
php_value post_max_size 1G

2.) In php.ini file, which is located in the php folder (like C:/xampp/php/php.ini)

upload_max_filesize = 1G
post_max_size = 1G

After modifying the global php.ini you will need to restart the webserver to have changes take effect.