Using WordPress ‘get_blog_id_from_url()’ PHP function

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The get_blog_id_from_url() WordPress PHP function retrieves a blog’s numeric ID using its URL.

Usage

For subdirectory installs:

$blog_id = get_blog_id_from_url("example.com", "/blog1/");

For subdomain installs:

$blog_id = get_blog_id_from_url("blog1.example.com");

Parameters

  • $domain (string) – Required. Website domain.
  • $path (string) – Optional. Not required for subdomain installations. Default: ‘/’.

More information

See WordPress Developer Resources: get_blog_id_from_url

Examples

Subdirectory Installation

This code retrieves the blog ID for a blog installed in a subdirectory, such as example.com/blog1/:

$domain = "example.com";
$path = "/blog1/";
$blog_id = get_blog_id_from_url($domain, $path);

Subdomain Installation

This code retrieves the blog ID for a blog installed on a subdomain, such as blog1.example.com:

$domain = "blog1.example.com";
$blog_id = get_blog_id_from_url($domain);

Get the blog ID and display it

This code retrieves the blog ID and displays it on the page:

$domain = "example.com";
$path = "/blog1/";
$blog_id = get_blog_id_from_url($domain, $path);
echo "Blog ID: " . $blog_id;

Get the blog ID for multiple blogs

This code retrieves the blog IDs for multiple blogs and stores them in an array:

$blogs = [
    ["domain" => "example.com", "path" => "/blog1/"],
    ["domain" => "example.com", "path" => "/blog2/"],
];

$blog_ids = [];

foreach ($blogs as $blog) {
    $blog_ids[] = get_blog_id_from_url($blog["domain"], $blog["path"]);
}

Check if a blog exists

This code checks if a blog exists by trying to get its blog ID:

$domain = "example.com";
$path = "/blog1/";
$blog_id = get_blog_id_from_url($domain, $path);

if ($blog_id) {
    echo "The blog exists!";
} else {
    echo "The blog does not exist.";
}