Open Control Panel in Windows 8.
Tip: While the process below works perfectly fine with Windows 8.1 and later, it's much faster using the Network Connections link that was first included on the Power User Menu with the 8.1 update. If you decide to use this shortcut, skip to Step 5.
In Control Panel touch or click on the Network and Internet link.
Note: You won't see this link if your Control Panel view is set to Large icons or Small icons. Instead, touch or click on Network and Sharing Center and move on to Step 4.
In the Network and Internet window, touch or click on Network and Sharing Center, most likely the link at the very top.
On the left margin of the Network and Sharing Center window, touch or click on Change adapter settings.
Note: I realize it says change in that link but don't worry, you won't be making changes to any network settings in Windows 8 in this tutorial. All you're doing is viewing the already configured default gateway IP.
On the Network Connections screen, locate the network connection that you want to view the default gateway IP for.
Tip: On most Windows 8 computers, your wired network connection is probably labeled Ethernet, while your wireless network connection is probably labeled Wi-Fi.
Note: Windows 8 can connect to multiple networks at the same time so you may see several connections on this screen. Usually, especially if your network connection is working, you can immediately exclude any connection that says Not connected or Disabled. If you're still having trouble determining which connection to use, change the view to Details and note the information in the Connectivity column.
Double-tap or double-click on the network connection. This should bring up an Ethernet Status or Wi-Fi Status dialog box, or some other Status, depending on the name of the network connection.
Note: If you instead get a Properties, Devices and Printers, or some other window or notification, it means that the network connection you chose does not have a status to show you, meaning it's not connected to a network or the Internet. Revisit step 5 and look again for a different connection.
Now that the connection's Status window is open, touch or click on the Details... button.
In the Network Connection Details window, locate either the IPv4 Default Gateway or IPv6 Default Gateway under the Property column, depending on which network type you're using.
The IP address listed as the Value for that property is the default gateway IP address Windows 8 is using at the moment.
Note: If no IP address is listed under either Property, the connection you chose in Step 5 may not be the one Windows 8 is using to connect you to the Internet. Check again that this is the right connection.
You can now use the default gateway IP address to troubleshoot a connection problem you might be having, to access your router, or whatever other task you had in mind.
Tip: Documenting your default gateway IP is a good idea, if only to avoid having to repeat these steps next time you need it. Unless you change your router's IP address, or your computer connects directly to a modem to access the Internet, the default gateway IP address used by Windows 8 will never be different.
Stolen from here
, dunno if that helps.