Public vs private IP addresses
Almost every device you use has two IP addresses at the same time: a public IP that the wider internet sees, and a private IP that only exists inside your own home or office network. They serve different jobs, and understanding the split clears up a lot of confusion about how your connection actually works. If you're new to the topic, our guide on what an IP address is covers the basics first.
What a public IP address is
Your public IP address is assigned by your Internet Service Provider (ISP) and belongs to your whole network rather than any single device. When your laptop, phone, and smart TV all reach out to the internet, websites see the same public address for all of them. This is the address shown when you check your IP on our home page.
Because it faces the outside world, the public IP is the one that carries a rough geographic signal. It can hint at your city or region and identify your ISP, though not your name or street address. Our guide on whether someone can find your location from your IP explains just how approximate that really is.
What a private IP address is
A private IP address is used only inside your local network (LAN). Your router hands these out automatically using DHCP (Dynamic Host Configuration Protocol), giving each device its own private address so the router can tell them apart. Private addresses never travel across the public internet, which is why the same ones can appear on millions of separate home networks at once.
The private IP ranges
Private addresses aren't chosen at random. A standard called RFC 1918 reserves three blocks specifically for private use, and every home and office network draws from them:
10.0.0.0/8— the range from10.0.0.0to10.255.255.255, common on larger networks.172.16.0.0/12— the range from172.16.0.0to172.31.255.255.192.168.0.0/16— the range from192.168.0.0to192.168.255.255, the one most home routers use.
That's why your laptop's address so often looks like 192.168.1.42. For the full breakdown of each block and what it's reserved for, see our reference on the private IP ranges.
How NAT ties the two together
You might wonder how dozens of devices, each with its own private address, all share a single public IP. The answer is NAT (Network Address Translation), a feature built into your router. When a device sends a request out, the router swaps the private source address for the public one and keeps a table of which reply belongs to which device. Incoming responses get translated back and delivered to the right machine.
NAT is also why private ranges can be reused everywhere without conflict. Since those addresses never appear on the public internet, one network's 192.168.1.10 has nothing to do with another network's 192.168.1.10. Only the public IP has to be globally unique.
How to find each address
Finding your public IP is the easy part: just check your IP with our tool, which shows it instantly without logging it. To find a device's private IP, look in your operating system's network settings, where it's listed next to your Wi-Fi or Ethernet connection. Our guide on how to find your local IP walks through the exact steps for Windows, macOS, Linux, and mobile.
Which one do I need?
It depends on the task. If you're setting up a printer, a media server, or port forwarding, you'll work with private IPs because those devices live inside your network. If you're giving someone remote access, configuring a firewall rule for outside traffic, or checking what a website sees, you'll want your public IP. Knowing which layer you're dealing with saves a lot of guesswork.