Free tool
IPv6 tool: compress, type and EUI-64
Enter an IPv6 address in any form. Get the shortest and the full form, the address type and the network for a prefix, and the EUI-64 interface ID from a MAC address. Every result comes with the steps.
The tool
The compression rules, in short
- An IPv6 address has 128 bits, written as 8 groups of 4 hexadecimal digits separated by colons.
- In each group you can drop the leading zeros:
0db8becomesdb8and0000becomes0. - The longest run of all-zero groups (at least two in a row) is replaced once with
::. On a tie, the first run is shortened. - Example:
2001:0db8:0000:0000:0000:ff00:0042:8329becomes2001:db8::ff00:42:8329.
All the rules, address types, EUI-64 and SLAAC are explained in the guide IPv6 addresses explained.
Frequently asked questions
How do I compress an IPv6 address?
Drop the leading zeros in every group, then replace the longest run of all-zero groups (at least two in a row) with ::. The :: can appear only once in an address.
Why can I not use :: twice?
Because an address always has exactly 8 groups. With one :: you know how many zero groups are missing; with two, you could not tell how many each one hides.
What is EUI-64?
A way for a device to build its own interface ID (the last 64 bits) from its MAC address: insert FFFE in the middle and flip the seventh bit of the first byte. It is used, for example, for link-local addresses and SLAAC.
Which address types does the tool recognise?
Global unicast, link-local (fe80::/10), unique local (fc00::/7), multicast (ff00::/8), loopback (::1), the unspecified address (::), documentation addresses (2001:db8::/32), IPv4-mapped addresses and reserved ranges.
Are the addresses I type sent anywhere?
No. Everything is calculated in your browser, and the addresses never leave your device.
Make IPv6 simple
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