How to get tenant ID from subscription ID

 1. First run the command below in powershell, substituting the subscription ID into the last line.

function Get-TenantIdFromSubId ($subId) {

    $url = "https://management.azure.com/subscriptions/$($subId)?api-version=2015-01-01"

    try {

        Invoke-WebRequest -Uri $url -Method Get -ErrorAction Stop

    } catch {

        # Extract the Tenant ID from the WWW-Authenticate header in the 401 response

        $authHeader = $_.Exception.Response.Headers["WWW-Authenticate"]

        if ($authHeader -match "https://login.windows.net/([a-f0-9-]+)") {

            return $matches[1]

        }

    }

    return "Tenant not found or ID invalid."

}

# Usage:

Get-TenantIdFromSubId "your-subscription-id-here"

2. After you get your tenant ID, go to the page below to identify the tenant.

https://sub2tenant.com/