How To Add Custom Image Sizes to the Add Media Dialog Box

Snippets by IsItWP

Do you want to add custom image sizes to the Add Media dialog box? With this little snippet, you can add custom image sizes to the Add Media dialog box.


All you have to do is add this code to your theme’s functions.php file or in a site-specific plugin.

Optionally add more image sizes to the if statement on line 1 through 3.

if ( function_exists( 'add_image_size' ) ) {
    add_image_size( 'new-size', 300, 100, true ); //(cropped)
add_filter('image_size_names_choose', 'my_image_sizes');
function my_image_sizes($sizes) {
        $addsizes = array(
                "new-size" => __( "New Size")
        $newsizes = array_merge($sizes, $addsizes);
        return $newsizes;

Note: If this is your first time adding code snippets in WordPress, then please refer to our guide on how to properly copy / paste code snippets in WordPress, so you don’t accidentally break your site.

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Comments   Leave a Reply

  1. 25 WordPress Code Snippets for Enhanced Performance - ManageWP April 9, 2014 at 11:20 am

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    1. For the life of me I can’t add a new media size to the “add media” section of my WP post editor. In media settings, I have changed the sizes and that didn’t work. I added code to the functions.php file in a child theme and that didn’t work either. I regenerated all thumbnails, and checking the server I can see the new file sizes are created.

      In my media settings, I have max width as 1367 to match my theme content area. File sizes on the server are 1376 wide. When I add the “Large” image to my post it actually adds the 1376 wide file but adds width=840 to the code and I can’t find where that setting is.

      1. You may want to check that the theme itself is not affecting the new image size.

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