admin_post_thumbnail_size filter

Note: When a theme adds ‘post-thumbnail’ support, a special ‘post-thumbnail’ image size is registered, which differs from the ‘thumbnail’ image size managed via the Settings > Media screen.

To use admin_post_thumbnail_size filter, first you have to register it using add_filter. You can write this code into functions.php of your activated theme or in a custom WordPress Plugin.

We at Flipper Code, always prefer to create a custom WordPress Plugin while using hooks so nothing breaks when you update your WordPress Theme in the future.

In the below live example, we have defined a function modify_admin_post_thumbnail_size_defaults which takes 3 parameters and we registered using add_filter. The first parameter admin_post_thumbnail_size is name of the hook, The second parameter modify_admin_post_thumbnail_size_defaults is name of the function which need to be called, third parameter is the priority of calling the hook if same hook is used multiple times and the last parameter is the number of arguments (if any) to be passed in the registered function.

Sometime, you have to remove a registered hook so you can use remove_filter to remove admin_post_thumbnail_size filter.


    Below are the 3 parameters are required to use this hook.

  • $size : (string|int[]) Requested image size. Can be any registered image size name, or an array of width and height values in pixels (in that order).
  • $thumbnail_id : (int) Post thumbnail attachment ID.
  • $post : (WP_Post) The post object associated with the thumbnail.

Live Example

apply_filters( 'admin_post_thumbnail_size', string|int[] $size, int $thumbnail_id, WP_Post $post )

Below is an example how you can use this hook.

                        function modify_admin_post_thumbnail_size_defaults($size, $thumbnail_id, $post) { 
                            // Update the $size variable according to your website requirements and return this variable. You can modify the $size variable conditionally too if you want.

                            return $size; 
                        // add the filter
                        add_filter( "admin_post_thumbnail_size", "modify_admin_post_thumbnail_size_defaults", 10, 3 );

To remove a hook callback, use the example below.

remove_filter( "admin_post_thumbnail_size", "modify_admin_post_thumbnail_size_defaults", 10, 3 );

Please make sure provide the same callback function name, priority and number of arguments while removing the hook callback.

Flipper Code is a Premium WordPress Plugins development company and integrating new functionalites into WordPress sites in form of custom WordPress Plugins since 2012. If you’re having any trouble using this hook, please contact our WordPress Development Team and we’d be happy to assist you.


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