Public vs. Private IP Addresses: What You Need to Know

Check your network settings, or use ipconfig on Windows or ipconfig getifaddr en0 on some Macs, to find a local address such as 192.168.1.45. Open a public IP checker and you may see a different address, such as the documentation example 198.51.100.47.

Both are your IP address. They're just from two completely different networks — and confusing them causes real problems.

Two Networks, Two Addresses

In a typical home IPv4 network, devices use local addresses and the router translates outgoing connections.

Your private network — a router or organization may assign private addresses to devices. The same private range can be reused by many separate networks; these addresses are not routed directly across the public internet.

The public side — a website sees the address used by your connection to reach it. This may be your router’s public IPv4 address, an ISP gateway, or a VPN endpoint. IPv6 uses a different addressing pattern.

How NAT Makes This Work

Network Address Translation (NAT) is what lets 10 devices in your home share a single public IP address.

Here's what happens when you load a webpage:

1. Your laptop (192.168.1.45) sends a request to your router
2. Your router rewrites the sender address to its public IP (198.51.100.47) and forwards the request
3. The website sends the response back to 198.51.100.47
4. Your router remembers which internal device made the request and delivers the response to 192.168.1.45

In this common IPv4 setup, the router translates the request and returns the response to the right local device. Other networks, including IPv6 and carrier-grade NAT, can behave differently.

Private IP Ranges (What to Recognize)

Private IP addresses fall into three reserved ranges that never appear on the public internet:

If an IP address starts with any of these patterns, it's private. It belongs to a local network. Millions of routers use 192.168.1.1 as their default gateway simultaneously — there's no conflict because these addresses never hit the public internet.

When You Actually Need to Know Your Public IP

Remote access. A private address alone will not identify a home device from outside the network. A public address may also be insufficient when an ISP uses carrier-grade NAT or your router blocks incoming traffic.

IP allowlisting. A service may ask for the public exit address seen from your office connection. Verify it from that network, especially if a VPN or proxy is involved.

VPN verification. Compare the address shown by What Is My IP before and after connecting. A change can confirm the route used for that specific request; it does not prove that every application uses the VPN.

Troubleshooting connectivity. If two devices on the same network can't communicate, knowing which is using a conflicting private IP can identify the problem.

Check Both in Seconds

What Is My IP shows the address used for that request. Other requests may use another protocol, VPN route, or connection. For a local address, check your device’s network settings or router admin panel.

Know which one you need before you share it. They're not interchangeable.

Frequently Asked Questions (FAQ)

Can another person on my Wi-Fi have the same private IP? Devices normally need distinct local addresses on the same network. A conflict can cause connectivity problems.

Does a VPN change my private IP? It may add a virtual network interface and change the public IP seen by sites, but your local Wi-Fi address can remain.

Is my public IP my physical location? No. It identifies a network endpoint and can map only approximately to a place.