“Add Media” only shows “Full Size” under Attachment Display Settings
In order to show new image dimension options in the WordPress admin media library you would need to use the image_size_names_choose filter to assign them a name. So the code in your functions.php should look something like this: if ( function_exists( ‘add_image_size’ ) ) { add_image_size( ‘single-post-medium’, 515 ); add_image_size( ‘single-post-small’, 250 ); } add_filter( … Read more