Add Media Library Column: File Size

functions.php

<?php
// Add Media Library Column: File Size
// Need help: https://bloggerpilot.com/snippet-media-filesize/

add_filter('manage_upload_columns', 'bp_add_column_file_size');
add_action('manage_media_custom_column', 'bp_column_file_size', 10, 2);
add_action('admin_head', 'bp_add_media_styles');

// Create the column
function bp_add_column_file_size($columns)
{
  $columns['bpFilesize'] = __('File Size');
  return $columns;
}
// Display the file size
function bp_column_file_size($column_name, $media_item)
{
  if ('bpFilesize' != $column_name || !wp_attachment_is_image($media_item)) {
    return;
  }
  $bpFilesize = filesize(get_attached_file($media_item));
  $bpFilesize = size_format($bpFilesize, 2);
  echo $bpFilesize;
}
// Format the column width with CSS
function bp_add_media_styles()
{
  echo '<style>.column-bpFilesize {width: 10px;}</style>';
}