The Difference Between IPv4 and IPv6

IPv4 and IPv6 are the two versions of the addressing system the internet uses to identify devices. IPv4 is the older standard that still runs most of the internet, while IPv6 is the newer one built to solve a problem IPv4 could not: running out of addresses. This guide explains the practical differences between them in plain language, and what, if anything, they mean for you. (For the basics first, see what an IP address is.)

The Core Problem IPv6 Solves

The whole reason IPv6 exists comes down to numbers. IPv4 uses 32-bit addresses, which allow for about 4.3 billion unique addresses. In the early days of the internet that seemed like more than enough. But with billions of phones, computers, smart TVs, and connected devices now online, the world simply ran out of fresh IPv4 addresses.

IPv6 was created to fix this permanently. It uses 128-bit addresses, which provide an almost unimaginable number of them, roughly 340 undecillion, a number so large it is effectively limitless for any foreseeable future. Where IPv4 is a small town’s worth of addresses, IPv6 is enough to give every grain of sand on Earth many addresses of its own.

How They Look Different

The two formats are easy to tell apart at a glance.

An IPv4 address is four numbers separated by dots, each from 0 to 255, like 192.168.1.1 or 203.0.113.45. This is the familiar format most people have seen.

An IPv6 address is longer, written as eight groups of letters and numbers separated by colons, like 2001:0db8:85a3:0000:0000:8a2e:0370:7334. To keep them manageable, IPv6 addresses are often shortened by removing leading zeros and collapsing long runs of zeros, so the same address might appear as 2001:db8:85a3::8a2e:370:7334.

The Key Differences at a Glance

Feature	IPv4	IPv6
Address length	32-bit	128-bit
Number of addresses	About 4.3 billion	About 340 undecillion
Format	Four numbers with dots	Eight groups with colons
Written example	192.168.1.1	2001:db8:85a3::8a2e:370:7334
Address setup	Often needs NAT	Direct addressing, no NAT needed
Security	Optional add-on	Built into the design
Configuration	Often manual or DHCP	Can self-configure

Beyond Just More Addresses

The bigger address pool is the headline, but IPv6 brings other improvements that matter under the hood.

No need for NAT. Because IPv4 ran short of addresses, homes shared a single public address among all their devices using a workaround called Network Address Translation, or NAT. IPv6 has so many addresses that every device can have its own, removing the need for that workaround and simplifying how devices connect directly.

Built-in security. IPv6 was designed with support for IPsec, a set of security features for encrypting and authenticating traffic, as part of the standard. With IPv4, that protection was an optional add-on rather than built in.

Simpler automatic setup. IPv6 includes a feature that lets devices configure their own addresses automatically when they join a network, with less reliance on the separate systems IPv4 typically needs.

More efficient routing. IPv6 uses a streamlined packet header that can make it more efficient for network equipment to process traffic, which can help performance as adoption grows.

Why Both Still Exist Together

You might expect the internet to have switched fully to IPv6 by now, but the transition is gradual. There is an enormous amount of equipment, software, and infrastructure built around IPv4, and replacing it all takes time. Rather than a sudden switch, IPv4 and IPv6 run side by side, an approach called dual-stack, where devices and networks support both at once.

For most people, this happens invisibly. Your devices and your internet provider handle which version to use automatically, choosing IPv6 where it is available and falling back to IPv4 where it is not. The two will likely coexist for many years until IPv6 becomes universal.

What This Means for You

For everyday use, the honest answer is that you do not need to do anything. Your devices, router, and internet provider manage IPv4 and IPv6 automatically, and you can browse, stream, and connect without ever thinking about which version is in use.

Understanding the difference still helps in a few situations. It explains why your home network uses private IPv4 addresses like 192.168.1.1 internally, even as IPv6 operates in the background. It clarifies why some network settings list both an IPv4 and an IPv6 address for your connection, which you can check with our what is my IP address tool. And it is useful context if you ever adjust advanced router settings, where you may see options for each version.

Conclusion

The difference between IPv4 and IPv6 comes down to IPv4 being the older standard with a limited supply of about 4.3 billion addresses, and IPv6 being the newer one with a virtually unlimited supply, plus built-in security and simpler addressing. The two run side by side today, and the transition to IPv6 is happening gradually in the background. The good news is that you do not need to do anything, since your devices and provider manage both automatically, but knowing the difference helps make sense of the addresses and settings you encounter on your network.