There are three methods to increase the file upload size.

1. functions.php in the Theme Folder

There are cases where we have seen that just by adding the following code in the theme function’s file, you can increase the upload size:

@ini_set('upload_max_size', '64M');
@ini_set('post_max_size','64M');
@ini_set('max_execution_time','300');

2. Create or Edit php.ini File

In most cases if you are on a shared host, you will not see a php.ini file in your directory. If you do not see one, then create a file called php.ini and upload it in the root folder. In that file add the following code:

upload_max_filesize = 64M
post_max_size = 64M
max_execution_time = 300

3. In .htaccess file

Add the below lines in .htaccess filein the root folder and add the following code:

php_value upload_max_filesize 64M
php_value post_max_size 64M
php_value max_execution_time 300
php_value max_input_time 300