IPv4 vs IPv6: what's the difference?
The two versions of internet addresses, explained simply.
IPv4 and IPv6 are two versions of the internet's addressing system. IPv4 is the original and looks like 203.0.113.42. IPv6 is its much larger replacement and looks like 2001:db8::8a2e:370:7334. Most devices today use both at once.
The key differences
| IPv4 | IPv6 | |
|---|---|---|
| Address length | 32 bits | 128 bits |
| Format | Four numbers, 0 to 255, separated by dots | Eight groups of hexadecimal digits separated by colons |
| Total addresses | About 4.3 billion | About 340 undecillion (3.4 × 1038) |
| Introduced | 1981 | 1998 (standardized), with wide rollout since the 2010s |
| Sharing | Homes share one public IP through NAT | Each device can have its own public address |
| Setup | Usually DHCP from your router | Devices can configure themselves (SLAAC) |
Why IPv6 exists
4.3 billion IPv4 addresses sounded like plenty in 1981. Today there are more phones, laptops, TVs and smart devices than that. The regional registries ran out of fresh IPv4 addresses in the 2010s, and IPv4 addresses are now bought and sold. IPv6 has so many addresses that running out isn't a practical concern.
How IPv6 addresses are shortened
Leading zeros in each group can be dropped, and one run of all-zero groups can be replaced with ::. So 2001:0db8:0000:0000:0000:0000:0000:0001 becomes 2001:db8::1.
Do I have IPv6?
Open ipfind.org. If your connection supports IPv6, your IPv6 address appears under your main IPv4 address. Many home and mobile providers in the US now support IPv6.
Is IPv6 faster or safer?
Speed is about the same; sometimes IPv6 is slightly faster because it avoids address translation. For privacy, modern devices use temporary IPv6 addresses that change regularly. If you use a VPN, make sure it handles IPv6 too, or your real IPv6 address can leak. See how to test your VPN.
Frequently asked questions
Should I turn off IPv6?
Usually not. Turn it off only if your VPN doesn't support IPv6 and is leaking your real IPv6 address.
Can IPv4 and IPv6 work together?
Yes. Most devices run both at once ("dual stack") and use whichever a website supports.
Why are IPv6 addresses so long?
They are 128 bits instead of 32, which gives about 340 undecillion possible addresses, enough for every device for the foreseeable future.