I'm working on a theme that has a number of image sizes defined correctly using:

add_image_size( 'name', 500, 200, true );

I would like to override these defined sizes from the child theme:

add_image_size( 'new-name', 400, 300, true );

I know I can add new sizes, but if I add the same name i.e:

add_image_size( 'name', 400, 300, true );

Then the parent function call is used - the child one is ignored - adding extra rules adds extra images which will never be used - it's not so bad, but it's not efficient.

Is there a function to de-register an added image size?



  • Can you please post the entire code that is relevant? Are the add_image_size() calls just sitting nakedly in functions.php, or are they properly wrapped inside a callback, and hooked into after_setup_theme? Knowing which is critical to answering your question. Commented Dec 4, 2012 at 16:31
  • hi chip - thanks for your comment - you're right it's wrapped in after_setup_theme - so this is all about priorities again - I always miss that!
    – Q Studio
    Commented Dec 4, 2012 at 17:37

3 Answers 3


The add_image_size( $name, $width, $height, $crop ) function is graceful enough to handle multiple calls using the same $name. It simply overwrites the existing value:

$_wp_additional_image_sizes[$name] = array( 'width' => absint( $width ), 'height' => absint( $height ), 'crop' => (bool) $crop );

So that means that all you need to do to override the parent Theme's definition of the custom image size is to ensure that your call to add_image_size() fires after the parent Theme's call.

Assuming that the Parent Theme does like so:

function parent_theme_setup() {
    add_image_size( 'name', 500, 200, true );
    add_image_size( 'new-name', 400, 300, true );
add_action( 'after_setup_theme', 'parent_theme_setup' );

Then the parent Theme's add_image_size() call fires at the after_setup_theme hook, at the default priority (i.e. 10).

(Note: if the calls are not wrapped in a callback, then they fire at the plugins_loaded hook, at priority 10.)

Here's the critical part: the child Theme's functions.php file is parsed before the parent Theme's, so if you use the same hooks to fire your add_image_size() calls, they'll get overridden by the parent Theme's add_image_size() calls.

The solution is to use a later hook or a lower priority, to ensure that the child Theme's add_image_size() call fires after the parent Theme's.

This should do the trick, regardless of how the parent Theme fires its calls:

function child_theme_setup() {
    add_image_size( 'name', 400, 300, true );
add_action( 'after_setup_theme', 'child_theme_setup', 11 );

Note that we use the same after_setup_theme hook, but use a lower priority (i.e. 11 instead of 10. Callbacks fire in order from higher priority (lower number) to lower priority (higher number), starting with priority 0. So a callback hooked into priority 11 will fire after a callback hooked into priority 10.

Note also that the after_setup_theme hook itself fires after the plugins_loaded hook, so this callback will still override the parent Theme, even if the parent Theme is _doing_it_wrong() by not wrapping such calls in an appropriate callback, hooked into an appropriate hook.

  • excellent - thanks chip! - I had them both on the same priority - notched the child back after the parent and all working fine.
    – Q Studio
    Commented Dec 4, 2012 at 17:41
  • I can't seem to overwrite the value if a plugin is calling add_image_size :(
    – Zhianc
    Commented Apr 22, 2015 at 12:57
  • took a long time to find this answer. thank you! Commented Jan 5, 2021 at 15:43

If someone wants to simply unset the additional image sizes, as opposed to changing the dimensions, use remove_image_size( string $name ), e.g.

function pinboard_child_theme_setup( $sizes) {

    $image_size_names = array('thumbnail', 'medium', 'large',
        'slider-thumb', 'blog-thumb', 'teaser-thumb', 'gallery-1-thumb',
        'gallery-2-thumb', 'gallery-3-thumb', 'image-thumb', 'video-thumb');

    $image_size_names_length = count($image_size_names);
    for($x = 0; $x < $image_size_names_length; $x++) {
add_action( 'after_setup_theme', 'pinboard_child_theme_setup', 11);

In your chile theme you would need to use add_action( 'after_setup_theme','new-name');

  • new-name here is the name of function or what ever name you are using for your main function
    – robin
    Commented Dec 4, 2012 at 16:07
  • Add an explanation to your answer: why and how does it solve the problem? Note that new-name is an invalid callback name.
    – fuxia
    Commented Dec 4, 2012 at 16:53
  • "new-name" is simply the handle of the image size being added.
    – Q Studio
    Commented Dec 4, 2012 at 17:42

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