An IPv4 address is a set of four numbers that identifies your device on the internet

An IPv4 address is how the internet finds your computer, phone, or printer. It looks like four numbers separated by dots: 192.168.1.5 or 8.8.8.8. Each number can be anywhere from 0 to 255. When you send an email, load a webpage, or stream video, your device uses this address so the data knows where to come back to — the same way a mailing address tells the post office where to deliver a letter.

IPv4 stands for Internet Protocol version 4. It has been the standard way devices talk to each other online since the 1980s. Every device that connects to the internet needs one: your laptop, your phone, your smart TV, your printer. Without it, nothing on the network would know how to reach you.

Key Takeaways

  • An IPv4 address is four numbers (0–255 each) separated by dots that identify your device on a network or the internet.
  • Your internet service provider assigns a public IPv4 address to your home router, and your router assigns private addresses to devices inside your home.
  • You can find your device's IPv4 address in your network settings, and your router's address is usually printed on the device itself or in its manual.
  • IPv4 addresses are running out because there are only about 4.3 billion possible combinations, so a newer system called IPv6 is gradually replacing it.

Public addresses versus private addresses

There are two kinds of IPv4 addresses: public and private. Your internet service provider (ISP) assigns a public address to your home router — this is the address the rest of the internet sees when you browse or send data. Private addresses are used only inside your home network. Your router assigns a private address to each device you connect: your laptop might be 192.168.1.10, your phone might be 192.168.1.11, your printer might be 192.168.1.20.

Private addresses always start with 10, 172, or 192 — these ranges are reserved for home and office networks. Your router acts as a translator: when your laptop sends a request to Google, the router changes the private address to the public address so Google knows where to send the answer back. This system lets you have dozens of devices at home without each one needing its own public address from your ISP.

How to find your IPv4 address

On Windows, open Settings, go to Network & Internet, then Status. Scroll down and click "View your network properties." Look for "IPv4 address" — that is your device's private address on your home network.

On Mac, open System Settings, click Network, select your connection, and look for "IPv4 address" in the details. On an iPhone or iPad, go to Settings, Wi-Fi, tap the network you are connected to, and scroll to see the IPv4 address listed as "IP Address."

To find your public address — the one your ISP assigned to your router — you can visit a website like whatismyipaddress.com or straightforward search "what is my IP" in Google. Your router itself usually has a sticker on the back or bottom with its address printed on it, often something like 192.168.1.1 or 192.168.0.1. Type that address into your web browser to log into your router's settings.

Why IPv4 addresses are running out

IPv4 allows for about 4.3 billion unique addresses. That seemed like plenty in the 1980s, but the internet has grown far beyond what anyone expected. Smartphones, tablets, smart home devices, security cameras, and connected cars all need addresses. Many organizations also hold large blocks of addresses they do not fully use, which wastes the remaining supply.

Because of this shortage, a new system called IPv6 is gradually being introduced. IPv6 addresses use a different format (like 2001:0db8:85a3:0000:0000:8a2e:0370:7334) and allow for vastly more combinations — enough that every grain of sand on Earth could have its own address many times over. However, IPv4 is still the dominant system, and most devices and networks support both old and new addresses at the same time.

What happens when your IPv4 address changes

Your ISP can change your public IPv4 address without warning. This usually happens when you restart your modem, when your ISP performs maintenance, or straightforward on a schedule — many ISPs reassign addresses every few months. If you run a server or host a website from home, a changing address is a problem, so you can pay your ISP for a static IP (one that does not change) instead of a dynamic one (which does).

Your private addresses inside your home are more stable. Your router assigns them based on rules you can sometimes adjust, but most home users never need to think about this. If you unplug a device and plug it back in, it usually gets the same private address it had before.

IPv4 addresses and network security

Knowing someone's IPv4 address does not let them hack your device directly — your router and firewall sit between the internet and your home network. However, your public address does reveal your general location (usually your city or region) and your ISP. Websites you visit can see your public address in their logs, which is how they know roughly where you are.

If you want to hide your public address from websites, you can use a VPN (virtual private network), which routes your traffic through another server so websites see the VPN's address instead of yours. This is useful for privacy but does not protect you from malware or phishing — those threats depend on what you click and read, not your IP address.

Frequently Asked Questions

Can two devices have the same IPv4 address?

Not on the same network. If two devices somehow get the same address, they will interfere with each other and neither will work properly. Your router is designed to prevent this by assigning each device a unique private address. On the public internet, your ISP makes sure no two customers have the same public address at the same time.

Is my IPv4 address the same as my MAC address?

No. Your MAC address identifies your device on a local network (like your home Wi-Fi), while your IPv4 address identifies it on the internet. They serve different purposes. Your router uses your MAC address to send data to the right device inside your home, then uses your IPv4 address to talk to the outside world.

What does it mean if I see 127.0.0.1 as my IPv4 address?

That is your device talking to itself — it is called the loopback address. You will see this if you are testing software on your own computer or if something is wrong with your network connection. It means your device is not actually connected to a network or the internet.

Do I need to memorize my IPv4 address?

No. Your device and router handle it automatically. The only time you might need to know it is if you are troubleshooting a network problem, setting up port forwarding, or connecting to your device remotely. Even then, you can look it up in seconds.