is_main_site( int $site_id = null, int $network_id = null )

Determine whether a site is the main site of the current network.

Parameters Parameters


(int) (Optional) Site ID to test. Defaults to current site.

Default value: null


(int) (Optional) Network ID of the network to check for. Defaults to current network.

Default value: null

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Return Return

(bool) True if $site_id is the main site of the network, or if not running Multisite.

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More Information More Information

Replaces function is_main_blog(), deprecated since 3.0.0. (wp-includes/ms-deprecated.php)

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Source Source

File: wp-includes/functions.php

function is_main_site( $site_id = null, $network_id = null ) {
	if ( ! is_multisite() ) {
		return true;

	if ( ! $site_id ) {
		$site_id = get_current_blog_id();

	$site_id = (int) $site_id;

	return get_main_site_id( $network_id ) === $site_id;

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Changelog Changelog

Version Description
4.9.0 The $network_id parameter was added.
3.0.0 Introduced.

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