In WordPress versions prior to 2.5 we could see the Page and post IDs in the WordPress admin panel. But from WordPress 2.5 and later, these are not displayed directly in your dashboard.
Here’s how you can find the IDs in WordPress 2.5 and later.
One Way
After you’ve logged into your WordPress dashboard, Go to Manage > Pages and from the list of Pages hover over the Page title you want to find the ID of. Every time you hover over, your browser’s status bar will show you a URL ending with a number like this.
http://www.xyz.com/wp-admin/page.php?action=edit&post=10
The number with which the URL ends is the Page ID (10 in this case).
Another
If you don’t see anything when you hover over, click on the Page link to open edit Page screen. Now, look in your browser’s address bar and you’ll find the URL ending with a number. and that is your Page ID.
Again, the number with which the URL ends is the Page ID (10 in this case).