Get Root Domain of a WordPress Multisite Network

August 19, 2016

The functions below can be used to get the root domain of a WordPress site. If the site is a multisite network and you’re on, calling km_get_root_domain() would return for instance. It also works on single-site WP installations.

* Get the root domain of the site/network.
* @return string|bool The root domain or false on failure.
function km_get_root_domain() {
$url_parts = parse_url( km_get_main_site_url() );
if ( $url_parts && isset( $url_parts['host'] ) ) {
return $url_parts['host'];
return false;
* Get the home URL of the main site.
* @return string The home URL of the main site.
function km_get_main_site_url() {
// This is the current network's information; 'site' is old terminology.
global $current_site;
if ( is_multisite() && $current_site ) {
$main_site_blog_id = $current_site->blog_id;
return get_home_url( $main_site_blog_id );
return home_url();

Kellen Mace

Written by Kellen Mace, who lives in Rochester Hills, MI and builds cool stuff on the web. About Kellen // Follow him on Twitter →