IPv4 vs IPv6: What's the Difference?

If you’ve ever looked at your IP address, you may have noticed that some addresses look like 192.168.1.25, while others look more like 2001:db8:1234:5678::1.

These are two different versions of the Internet Protocol: IPv4 (Internet Protocol version 4) and IPv6 (Internet Protocol version 6). Both are used to identify devices and networks so that data can travel across networks.

The biggest difference in the IPv4 vs IPv6 comparison is simple: IPv4 uses 32-bit addresses, while IPv6 uses 128-bit addresses. That difference gives IPv6 an enormously larger address space.

IPv6 wasn’t created simply because the numbers looked nicer — it was developed primarily because the internet needed far more unique IP addresses than IPv4 could ever provide.

IPv4 vs IPv6: Quick Comparison

The most important difference between IPv4 and IPv6 is the size of the address space.

What Is IPv4?

IPv4 is the fourth version of the Internet Protocol and has been used to connect internet-enabled devices for decades.

An IPv4 address contains 32 bits and is normally written as four decimal numbers separated by periods, for example: 192.168.1.25. Each section can range from 0 to 255, which is why IPv4 addresses look relatively short and familiar.

Example public IPv4: 203.0.113.42. Example private IPv4: 192.168.1.25.

IPv4 has approximately 4.3 billion possible addresses. That sounded enormous when IPv4 was designed, but the internet eventually grew far beyond what its original address space could comfortably accommodate.

What Is IPv6?

IPv6 is the newer version of the Internet Protocol, designed with a vastly larger address space. Instead of 32-bit addresses, IPv6 uses 128-bit addresses, for example: 2001:db8:1234:5678::1.

IPv6 addresses use hexadecimal numbers and colons rather than decimal numbers and periods. Because IPv6 uses 128 bits, its theoretical address space is enormous — 2¹²&sup8; addresses, or approximately 340 undecillion addresses. In practical terms, an IPv4 vs IPv6 comparison isn’t close: IPv6 provides vastly more address space than IPv4.

Why Was IPv6 Created?

The internet kept growing. More computers, smartphones, tablets, servers, smart TVs, cameras, IoT devices, cars, industrial systems, and connected appliances all needed network addresses.

IPv4’s roughly 4.3 billion addresses were not enough to provide every device with a unique, globally routable address. Technologies such as NAT (Network Address Translation) helped extend the useful life of IPv4 by allowing many devices to share a single public IPv4 address.

For example, a laptop at 192.168.1.10, a phone at 192.168.1.11, and a TV at 192.168.1.12 can all connect through the same router, which shares one public IPv4 address such as 203.0.113.42 with the wider internet.

But NAT doesn’t create more IPv4 addresses — it simply allows multiple private devices to share the available public addresses. IPv6 solves the underlying shortage by providing a fundamentally larger address space.

IPv4 vs IPv6 Address Format

This is probably the easiest difference to recognize. IPv4 uses four decimal sections called octets, e.g. 192.168.1.25. IPv6 uses eight groups of hexadecimal digits, e.g. 2001:0db8:1234:5678:0000:0000:0000:0001, which can be shortened using IPv6’s compression rules to 2001:db8:1234:5678::1.

The :: represents one or more consecutive groups of zeros. So although IPv6 addresses look much more complicated at first glance, the format allows them to be shortened considerably.

IPv4 vs IPv6: Address Space

This is the biggest technical difference between IPv4 and IPv6. IPv4 uses 32 bits; IPv6 uses 128 bits. That means IPv6 has 2&sup9;&sup6; times more addresses than IPv4.

You don’t need to memorize that number — the important takeaway is that IPv4 has a limited address space, while IPv6 has an extraordinarily large one. This makes IPv6 much better suited to a world where billions of devices need network connectivity.

Public IPv4 vs Private IPv4

You’re probably already familiar with private IPv4 addresses if you’ve used home Wi-Fi. Common private IPv4 ranges include 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16.

For example, 192.168.1.25 can be a private address assigned to your laptop by your router, while your internet connection might simultaneously have a public IPv4 address such as 203.0.113.42. Your router uses NAT to manage communication between local devices and the public internet.

If you want the full explanation of this distinction, see Public IP vs Private IP: What’s the Difference?

Does IPv6 Have Private IP Addresses?

IPv6 handles local addressing differently from IPv4. IPv6 uses Unique Local Addresses (ULAs) for private/local network communication, generally from the fc00::/7 range, intended for local communication rather than global internet routing.

IPv6 also uses link-local addresses, which begin with fe80::, used for communication on the local network segment. So don’t simply look for something resembling 192.168.x.x when trying to determine whether an IPv6 address is local.

IPv4 vs IPv6: NAT

NAT is extremely common in IPv4 networks: multiple devices on a home network can share the same public IPv4 address through the router. IPv6 was designed with enough address space that the protocol does not depend on NAT in the same way IPv4 networks commonly do.

That doesn’t mean every IPv6 network works without any form of address translation or firewalling — it means NAT isn’t required simply because there aren’t enough IPv6 addresses.

IPv4 vs IPv6: Which Is Faster?

There isn’t a simple answer. IPv6 isn’t automatically faster than IPv4. Actual performance can depend on your ISP, network architecture, routing, server location, DNS, peering, device, protocol, network congestion, and whether IPv4 or IPv6 is being used natively or through a transition mechanism.

On some networks IPv6 can perform very well; on others, IPv4 may currently provide the better route. Don’t choose an internet provider simply because it advertises IPv6 and assume that automatically means faster internet.

Does IPv6 Replace IPv4?

Not overnight. The internet today is a mixture of IPv4 and IPv6 networks. Many devices, operating systems, routers, and services support both — known as dual-stack operation.

For example, your computer could have an IPv4 address like 192.168.1.25 and an IPv6 address like 2001:db8:1234::25 at the same time. This allows devices and networks to communicate with systems using either protocol, and it’s one of the important ways the internet has been able to transition gradually instead of switching everything from IPv4 to IPv6 on a single day.

If your device and network have IPv6 connectivity and a website supports IPv6, your connection may use IPv6; if not, it falls back to IPv4 automatically. That’s why you might never consciously notice whether you’re using IPv4 or IPv6.

How Do I Know If I’m Using IPv4 or IPv6?

The easiest way is to use an IP checker. If the result looks something like 203.0.113.42, that’s IPv4. If it looks something like 2001:db8:1234::1, that’s IPv6. Some connections support both, so you may see both an IPv4 and an IPv6 address available.

Does a VPN Work With IPv4 and IPv6?

Yes, VPN services can support IPv4 and IPv6, but the exact behavior depends on the VPN provider and configuration. This matters because simply connecting to a VPN doesn’t mean every IPv6-related privacy issue automatically disappears.

A VPN should handle IPv6 traffic appropriately if you’re relying on it for IP privacy. This is one reason to look at a VPN’s IPv6 support and leak-protection behavior, rather than choosing purely based on price. See Compare VPN Services for a side-by-side breakdown, and Does a VPN Change Your IP Address? to see exactly what changes when you connect.

Is IPv6 More Private Than IPv4?

Not automatically — this is an important misconception. IPv6 has technical differences that affect addressing and network configuration, but simply using IPv6 doesn’t make you anonymous. Websites can still observe information associated with your connection, and other tracking mechanisms can still identify returning users.

An IPv6 address can provide network-level information in much the same general way a public IPv4 address can — things like network provider, organization, and approximate geographic region — but an IP address isn’t automatically a precise GPS location, and IP geolocation can be inaccurate, especially with VPNs, mobile networks, corporate networks, and proxies.

If your goal is to hide your public IP from websites, that’s a separate question from whether you’re using IPv4 or IPv6. See How to Hide Your IP Address for that.

IPv4 vs IPv6: Which One Should You Use?

For most users, this isn’t really a decision you need to make manually. Your ISP, router, operating system, and destination services largely determine which protocol is used. If your network supports IPv6 properly, your devices can use it; if a destination only supports IPv4, IPv4 remains necessary. That’s why dual-stack support remains useful during the transition, and why the IPv4 vs IPv6 debate rarely requires action from an everyday user.

Frequently Asked Questions

IPv4 vs IPv6: Final Verdict

IPv4 and IPv6 perform the same fundamental job: they provide addressing for network communication. But they’re built around very different address spaces.

IPv4 uses 32-bit addresses, giving it roughly 4.3 billion possible addresses. IPv6 uses 128-bit addresses, providing an enormous address space capable of supporting the continued growth of connected devices.

For everyday users, you don’t usually need to choose between IPv4 and IPv6 manually — your network may use one or both. The important thing is understanding which address you’re looking at: if you’re checking what websites can see, you’re generally interested in your public IP; if you’re troubleshooting your home network, you’re often dealing with your private IP. And if your goal is to change the public IP that websites see, that’s where VPNs become relevant.