IPv4 vs IPv6: what's the difference?

The internet runs on two addressing systems at the same time: IPv4, designed in the early 1980s, and IPv6, its successor. Your connection is almost certainly using one or both right now — you can check which on our homepage. This article explains why two systems exist, how they differ, and whether any of it requires action from you. If you first want a refresher on what an IP address actually does, start with what is an IP address.

Why IPv4 ran out of room

An IPv4 address is a 32-bit number, written as four groups of digits like 203.0.113.42. Thirty-two bits allow about 4.3 billion unique combinations (2 to the power of 32). In 1981, when the world had a few hundred connected computers, that seemed inexhaustible. Nobody anticipated that within four decades nearly every person on Earth would carry a connected device, with billions more sensors, TVs, cars, and servers on top.

The math simply stopped working. Large blocks had also been handed out generously in the early days, so the usable pool was smaller than the raw number suggests. The top-level pool ran dry in 2011, and the regional registries — including RIPE NCC, which serves Norway — have since exhausted their normal supplies. Today, "new" IPv4 addresses are mostly recycled ones, bought and sold on a secondary market where a single address can cost tens of dollars.

What IPv6 looks like

IPv6 solves the shortage with brute force: addresses are 128 bits long instead of 32. That allows 2 to the power of 128 combinations — roughly 340 undecillion, a number so large that every grain of sand on Earth could have trillions of addresses of its own. Address scarcity is permanently off the table.

The format changes too. Instead of four decimal numbers, IPv6 uses eight groups of hexadecimal digits separated by colons:

2001:0db8:0000:0000:0000:8a2e:0370:7334

Two shorthand rules keep this manageable: leading zeros in each group can be dropped, and one run of consecutive all-zero groups can be collapsed into a double colon. The address above is normally written as 2001:db8::8a2e:370:7334. Longer to type than an IPv4 address, certainly — but almost nobody types IP addresses by hand anyway, since DNS translates names to addresses automatically (you can see this in action with our DNS lookup tool).

IPv4 vs IPv6 side by side

A note on security: IPv6 mandating IPsec support in the protocol does not mean IPv6 traffic is automatically encrypted. In practice, the encryption protecting your browsing is HTTPS, which works identically over both protocols. The real-world security difference between the two is smaller than comparison charts often imply.

Why the transition is taking decades

IPv6 was standardized in the 1990s, so why is IPv4 still everywhere? Two reasons stand out.

NAT took the pressure off

Network Address Translation (NAT) lets your entire household share a single public IPv4 address, with the router keeping track of which internal device each connection belongs to. Every home router does this by default — it is the reason your laptop's local address differs from the address websites see, as explained in local vs public IP. NAT stretched the IPv4 pool far beyond its natural limits and removed the urgency that would otherwise have forced a fast migration.

The two protocols cannot talk to each other

An IPv6-only device cannot reach an IPv4-only server without a translation gateway. Because neither side can drop the old protocol while the other still depends on it, most networks run dual stack: both protocols side by side, with devices preferring IPv6 when it is available and falling back to IPv4 when it is not. Running two systems in parallel works well, but it also means there is no hard deadline pushing anyone to finish the job — so the transition crawls along, driven mainly by mobile carriers and large content networks where IPv6 is cheaper to operate at scale.

What you actually notice as a user

Honestly: very little, and that is by design. A few practical differences do exist:

• Addresses look different. If a website or tool shows you a long colon-separated address instead of four numbers, you are connecting over IPv6.
• Each device can get its own public address. Without NAT in the way, things like game hosting, video calls, and peer-to-peer connections can work more directly over IPv6.
• Performance is usually a wash. On well-run networks IPv6 is sometimes marginally faster because it skips NAT processing, but the difference is rarely noticeable.
• Geolocation and lookups work on both. An IPv6 address reveals the same kind of information as an IPv4 address — provider and approximate region. You can inspect either type with our IP lookup tool.

Do you need to do anything?

For almost everyone, no. Modern operating systems, phones, and routers have supported IPv6 for years, and if your internet provider offers it, your devices are likely already using it silently. There is no switch to flip, nothing to buy, and no deadline to worry about. The dual-stack approach exists precisely so that ordinary users never have to care.

The exceptions are niche: if you host servers at home, manage a company network, or design address plans with a subnet calculator, you will eventually want to understand IPv6 addressing properly. And if you notice specific services misbehaving, some routers let you disable IPv6 as a troubleshooting step — though modern networks rarely need it.

How to check which one you are using

Visit the WhatsMyIP.no homepage. If you see an address with four dot-separated numbers, that connection used IPv4; a longer address with colons means IPv6. Many connections have both, in which case your browser chose one for the request — usually IPv6, since dual-stack devices prefer it when available.

Whichever protocol carries your traffic, the fundamentals stay the same: your provider assigns the address, it can change over time (see static vs dynamic IP), and it reveals your provider and rough location but not your identity. IPv6 changes the size of the address — not what it means for your privacy.