How to add a CSS Class to ul and anchor element of Tag Cloud generated through wp_tag_cloud function?

I want the default class for ul of wp-tag-cloud to be tag-cloud and anchor tag would have btn btn-xs btn-primary class.

<ul class="tag-cloud">
   <li><a class="btn btn-xs btn-primary" href="#">Apple</a></li>
   <li><a class="btn btn-xs btn-primary" href="#">Barcelona</a></li>
   <li><a class="btn btn-xs btn-primary" href="#">Ipod</a></li>

3 Answers 3


We can also modify the anchor CSS class with the wp_generate_tag_cloud_data filter (4.3+).

With that filter we can modify the following anchor data:

  • id
  • url
  • role
  • name
  • title (removed in 4.8)
  • slug
  • real_count
  • class
  • font_size
  • formatted_count (added in 4.8)
  • aria_label (added in 4.8)
  • show_count (added in 4.8)

The style attribute is hardcoded, as can be seen from the 4.8 version:

$a[] = sprintf(
    '<a href="%1$s"%2$s class="%3$s" style="font-size: %4$s;"%5$s>%6$s%7$s</a>',
      esc_url( $tag_data['url'] ),
      esc_attr( $class ),
      esc_attr( str_replace( ',', '.', $tag_data['font_size'] ) . $args['unit'] ),
      esc_html( $tag_data['name'] ),

Note that we can change the font-size unit with:

wp_tag_cloud( [ 'unit' => 'rem', 'smallest' => 1, 'largest' => 4 ] );

or e.g. with the widget_tag_cloud_args filter for the tag cloud widgets.


Here we append the btn btn-xs btn-primary classes to anchors in all tag clouds:

add_filter( 'wp_generate_tag_cloud_data', function( $tag_data )
    return array_map ( 
        function ( $item )
            $item['class'] .= ' btn btn-xs btn-primary';
            return $item;
        (array) $tag_data 

} );
  • Thanks. Does it support all the tags? I tried the style and it didn't work.
    – Johansson
    Jun 5, 2017 at 8:48
  • 1
    Alright i did. Also linked this question and insisted that @birgire requested a trac ticket for it ( JK ).
    – Johansson
    Jun 5, 2017 at 9:38
  • 2
    hehe best of luck with it ;-)
    – birgire
    Jun 5, 2017 at 9:39
  • 1
    But note you can modify the unit from pt to e.g. em
    – birgire
    Jun 5, 2017 at 9:42
  • 1
    You can modify the font-size unit but the style="font-size..." part is hardcoded. I thought you meant a ticket to make that more flexible, e.g. to be able to remove the font-size part completely with the wp_generate_tag_cloud_data ;-)
    – birgire
    Jun 5, 2017 at 9:49

The tags are wrapped in a DIV element in the latest WordPress version the day i'm writing this answer (4.7.5), and their class is tagcloud, so i will move to the next thing that is asked in the question.

The tags can be modified using the wp_generate_tag_cloud filter. By writing a preg_replace you can change the class to whatever you wish. Here is an example:

add_filter('wp_generate_tag_cloud', 'my_tag_cloud',10,1);
function my_tag_cloud($string){
   return preg_replace('/class="tag-link-.+ tag-link-position-.+"/', 'class="btn btn-xs btn-primary"', $string);

Anchors have the tag-link-X tag-link-position-Y class which X and Y are numbers.


The classes are hardcoded in wp_generate_tag_cloud() function. Your only option there is to modify final string output via wp_generate_tag_cloud filter.

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