The code in question →

<?php if ( has_post_thumbnail() ) {the_post_thumbnail();} ?>

The generated output in browser is like this →

<img width="1620" height="973" src="..../site04/wp-content/uploads/2018/01/audi_ileana.jpg" class="attachment-post-thumbnail size-post-thumbnail wp-post-image" alt="" srcset="..../site04/wp-content/uploads/2018/01/audi_ileana.jpg 1620w, http://......./site04/wp-content/uploads/2018/01/audi_ileana-300x180.jpg 300w, ....../site04/wp-content/uploads/2018/01/audi_ileana-768x461.jpg 768w, http://....../site04/wp-content/uploads/2018/01/audi_ileana-1024x615.jpg 1024w" sizes="(max-width: 1620px) 100vw, 1620px">

Anticipated result →

I want that height should output as "auto" value.

I tried this:

<div class="pimg">
    <?php if ( has_post_thumbnail() ) {the_post_thumbnail();} ?>

and its css:

.pimg img {max-with:100%; height:auto;}

2 Answers 2


You can use a filter to remove height and width attributes from images, as explained in this CSS Tricks. Place the following in your themes functions.php file.

add_filter( 'post_thumbnail_html', 'remove_width_attribute', 10 );
add_filter( 'image_send_to_editor', 'remove_width_attribute', 10 );

function remove_width_attribute( $html ) {
   $html = preg_replace( '/(width|height)="\d*"\s/', "", $html );
   return $html;
  • Is it safe to touch the core functions written by Automattic team? Are their any repercussion?
    – WordCent
    Jan 4, 2018 at 13:39
  • 1
    @TheWPNovice Filters where introduced to do exactly that. The repercussions are that you might break things, this is always a possibility. But in a case like this I'd guess you're fine
    – kero
    Jan 4, 2018 at 15:38

Alternatively you could try using another function to get just the url then echo that inside img:

<img src="<?php echo get_the_post_thumbnail_url(); ?>" alt="Post thumbnail image">

And style it completely yourself.

  • Yes, yes, but you forget to put that into esc_url → <img src="<?php echo esc_url(get_the_post_thumbnail_url()); ?>" alt="Post thumbnail image">
    – WordCent
    Jan 4, 2018 at 15:44

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