I'm using the following code to add a featured image to my rss feed in wordpress.

add_action( 'rss2_item', 'add_post_featured_image_as_rss_item_enclosure' );

function add_post_featured_image_as_rss_item_enclosure() {
if ( ! has_post_thumbnail() )

$thumbnail_size = apply_filters( 'rss_enclosure_image_size', 'thumbnail' );
$thumbnail_id = get_post_thumbnail_id( get_the_ID() );
$thumbnail = image_get_intermediate_size( $thumbnail_id, $thumbnail_size );

if ( empty( $thumbnail ) )

$upload_dir = wp_upload_dir();

    '<enclosure url="%s" length="%s" type="%s" />',
    filesize( path_join( $upload_dir['basedir'], $thumbnail['path'] ) ), 
    get_post_mime_type( $thumbnail_id ) 

But the plguin above is outputting a really small image 150x150. I tried changing the thumbnail size to full or large, but it won't work. Is there any way to add a url to the full featured image size in the enclosure field below?

Thanks in advance

2 Answers 2


You can use the get_post_thumbnail_id to get the ID of the thumbnail, then with the function wp_get_attachment_image_src you can get the image of the size you want, including full size, using the second paramenter.

$thumb_id = get_post_thumbnail_id(get_the_ID());    
$thumb_data = wp_get_attachment_image_src( $thumb_id, 'full');

Now in $thumb_data you have a nice array, or false if there's no image.

The array has this structure:

[0] => url

[1] => width

[2] => height

[3] => boolean: true if $url is a resized image, false if it is the original.


On the line below, you just need to change "thumbnail" at the end to "large". That should do the trick

$thumbnail_size = apply_filters( 'rss_enclosure_image_size', 'thumbnail' );

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