Public vs. Private IP Addresses: What You Need to Know
Type ipconfig on Windows or ifconfig on Mac and you'll see an address like 192.168.1.45. Open any "what's my IP" tool and you'll see something completely different, like 185.220.101.47.
Both are your IP address. They're just from two completely different networks — and confusing them causes real problems.
Two Networks, Two Addresses
Every device in your home lives on two networks simultaneously:
Your private (local) network — controlled by your router. It assigns private IP addresses to every device it manages. These addresses exist only inside your home. The internet has never heard of 192.168.1.45.
The public internet — controlled by your ISP. Your router gets one public IP address from the ISP and uses it to represent all your devices when communicating with the outside world.
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:
- Your laptop (
192.168.1.45) sends a request to your router - Your router rewrites the sender address to its public IP (
185.220.101.47) and forwards the request - The website sends the response back to
185.220.101.47 - Your router remembers which internal device made the request and delivers the response to
192.168.1.45
Your laptop never directly communicates with the outside internet. The router is the intermediary — the public face of your entire home network.
Private IP Ranges (What to Recognize)
Private IP addresses fall into three reserved ranges that never appear on the public internet:
| Range | Common Use | |---|---| | 10.0.0.0 – 10.255.255.255 | Large corporate networks | | 172.16.0.0 – 172.31.255.255 | Medium networks | | 192.168.0.0 – 192.168.255.255 | Home routers (most common) |
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. If you're SSH-ing into a home server, accessing a security camera remotely, or using a gaming server, you need to give someone your public IP — not your private one.
IP whitelisting. Many corporate tools, VPNs, and APIs restrict access by IP address. When you're asked to "whitelist your office IP," they want your public IP.
VPN verification. After connecting to a VPN, check your public IP with What Is My IP to confirm the VPN is actually routing your traffic — not just appearing to.
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 your public IP immediately — the address the rest of the internet sees when you connect. For your private IP, check your device's network settings or router admin panel.
Know which one you need before you share it. They're not interchangeable.
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