I want to change the size of the featured image

Hello all,

I have looked for a topic that deals with the same issue, but couldn’t find it. If there is one, please direct me to it and close this one :slight_smile:

I would really like to change the featured image size to fit a vertical image (the image I want to use as a featured image has an original size of 800x1200px). How would I go about changing that? My php knowledge only goes so far.

Thanks in advance,


Hi Mandy,

I hope you are well today and thank you for your question.

Do you want to change this featured image size on blog page or single post page or on both pages?

Please advise so that i can help you.

Kind Regards,

I would like it to have it changes on both pages.

I’m about to install the child theme, maybe I can get it to work in there. Even though I have no idea where to change it.

I’ve changed the functions.php, but that doesn’t seem to work:

function activello_setup() {

add_image_size( ‘activello-featured’, 800, 1200, true );


(I didn’t delete the … bits, that’s just to keep this post clear and to show you what I’ve done).

Am I correct that I should change the functions.php?

You can try achieving this by using the attached small plugin specially developed for you that contains the following custom code.

function modify_featured_image_size(){
    add_image_size( 'activello-featured', 1200, 1200, true );
add_action( 'init', 'modify_featured_image_size', 10 );