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IPv6

Also known as: Internet Protocol version 6

The 128-bit successor to IPv4, written in eight groups of hexadecimal digits like 2001:db8::1, providing 340 undecillion unique addresses.

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What is IPv6?

IPv6 (Internet Protocol version 6) is the current-generation Internet Protocol, designed to replace IPv4 once its address space was exhausted. IPv6 uses 128-bit addresses — 340 undecillion (3.4 × 10³⁸) unique values — enough to assign many orders of magnitude more addresses than IPv4 for every grain of sand on Earth. It was standardized in RFC 8200.

How IPv6 addresses are written

Addresses are written as eight groups of four hexadecimal digits separated by colons:

2001:0db8:85a3:0000:0000:8a2e:0370:7334

Two simplification rules compress most addresses:

  1. Leading zeros in each group may be omitted: 2001:db8:85a3:0:0:8a2e:370:7334
  2. One run of consecutive zero groups can be replaced with :: (but only once): 2001:db8:85a3::8a2e:370:7334

The loopback address is ::1, the unspecified address is ::, and the link-local range is fe80::/10. Global unicast addresses — the public routable range — all currently start with 2000::/3.

Advantages over IPv4

Beyond the expanded address space, IPv6 improves several aspects of the protocol:

  • Stateless address autoconfiguration (SLAAC) lets devices generate their own addresses without DHCP
  • Simplified packet headers speed up router processing
  • Built-in IPsec support (optional but standardized)
  • No need for NAT in typical home networks — each device can have its own globally routable address, which simplifies peer-to-peer applications

Most modern operating systems, ISPs, and mobile carriers support both IPv4 and IPv6 concurrently through dual-stack networking. Use our IPv6 expander/compressor tool to convert between compressed and expanded forms.

Frequently Asked Questions

An IPv6 address is written as eight groups of four hexadecimal digits separated by colons, such as 2001:0db8:85a3:0000:0000:8a2e:0370:7334. Shortcuts let you omit leading zeros and compress one run of zero groups as "::".
Usually slightly, but not dramatically. IPv6's simpler packet header and lack of NAT can reduce latency, but most real-world speed differences come from routing and peering rather than the protocol itself.
Not strictly. Most internet services are still reachable over IPv4. IPv6 is increasingly required by mobile carriers, large ISPs, and enterprises, and it enables direct peer-to-peer connectivity without NAT.
Yes, through dual-stack networking, where a device runs both protocol stacks simultaneously. Most modern operating systems, routers, and ISPs use dual-stack, preferring IPv6 when both ends support it and falling back to IPv4 otherwise.
Our IP lookup tool shows your current IPv4 and IPv6 addresses side by side. If only an IPv4 address is listed, your ISP or network does not route IPv6 traffic for you.
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