IPv4 vs IPv6: what's the difference?
Why there are two kinds of IP address and which one your connection uses.
There are two versions of IP address in use today. IPv4 is the original, and IPv6 is its much larger replacement. Most connections now support both, and websites see whichever one your device happened to use.
| IPv4 | IPv6 | |
|---|---|---|
| Example | 203.0.113.42 | 2001:db8::8a2e:370:7334 |
| Size | 32 bits | 128 bits |
| Possible addresses | About 4.3 billion | About 340 undecillion (a 39-digit number) |
| Written as | Four numbers 0–255, separated by dots | Eight groups of hexadecimal digits, separated by colons |
Why IPv6 exists
IPv4 was designed in the early 1980s, long before phones, laptops, TVs, and smart speakers all needed addresses. 4.3 billion addresses sounded endless then. The central pool of unused IPv4 addresses ran out in 2011, and the regional registries that hand addresses to providers have since run out or nearly run out too.
The internet kept working mostly thanks to a workaround called NAT, which lets many devices share one public IPv4 address. Your home router does exactly this. IPv6 fixes the shortage properly by offering so many addresses that every device can have its own.
How to read an IPv6 address
An IPv6 address has eight groups of four hexadecimal characters (0–9 and a–f). Two rules make them shorter:
- Leading zeros in a group can be dropped, so
0db8becomesdb8. - One run of groups that are all zero can be replaced with
::, but only once per address.
Which one do I have?
Our home page shows the address your connection used and, when available, the other version too. If you only see an IPv4 address, your provider or router may not support IPv6 yet. That's normal and doesn't slow down your browsing.
Last updated October 2026.