How to display the maximum upload size in a WordPress single site?

Question

I'm working on a WordPress single site, where in front end, below a custom made form, where I have a file upload feature, I need to display the maximum upload size.

In my local Laragon WAMP setup, the PHP post_max_size is set to 2G. I wanted to downgrade to only 20M (20 mb).

After searching and reading several blog articles, I put the following code in my theme's functions.php:

<?php
// Set upload size limit to 20mb.
@ini_set('upload_max_size', '20M');
@ini_set('post_max_size', '20M');
@ini_set('max_execution_time', '300');

/**
 * Filter the upload size limit for non-administrators.
 *
 * @param string $size Upload size limit (in bytes).
 *
 * @return int         Filtered size limit.
 */
function wpse_control_upload_size_limit( $size ) {
    if ( ! current_user_can( 'manage_options' ) ) {
        return 20971520; // 20mb to binary bytes.
    }

    return $size;
}

add_filter( 'upload_size_limit', 'wpse_control_upload_size_limit', 20 );

With this code in action, with a non-admin user I can see the Admin panel Upload New Media page is showing: Maximum upload file size: 20 MB.

Issue is: I want to display the same maximum file size limit information on my front end from.

What I tried so far is putting the following code in functions.php:

var_dump(@ini_get('post_max_size'));

But this is getting the 2G limit as it's not getting the WordPress setup.

I also tried by hooking this code in upload_size_limit with no luck:

add_action( 'upload_size_limit', function() {
    var_dump( @ini_get( 'post_max_size' ) );
});

I know there's a plugin named Increase Maximum Upload File Size, but I don't want to use a plugin for this feature. I'm also aware that, in multisite we've setup data from where we can get the maximum upload size.

But how can I display the maximum upload size on a front page form in single WordPress instance?

Answer 1

The answer actually lies on the same page where you inspected your modifications: /wp-admin/media-new.php.

If you get to the /wp-admin/media-new.php file, you will get a function:

<?php media_upload_form(); ?>

And the function is located in /wp-admin/includes/media.php, where you will get the following line:

$max_upload_size = wp_max_upload_size();

So the holly grail you are searching is: wp_max_upload_size().

So you can easily follow the core, and display the maximum uploaded size anywhere with the following bit of code (thanks to the core):

<?php
$max_upload_size = wp_max_upload_size();
if ( ! $max_upload_size ) {
    $max_upload_size = 0;
}

/* translators: %s: Maximum allowed file size. */
printf( __( 'Maximum upload file size: %s.', 'wpse355118' ), esc_html( size_format( $max_upload_size ) ) );
?>