IPv6 Expander/Collapser

Convert between expanded and compressed IPv6 address formats. Shorten IPv6 addresses.

Expand IPv6 Address

Expanded IPv6:

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Collapse IPv6 Address

Collapsed IPv6:

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About IPv6 address formats

IPv6 addresses are 128-bit numbers, typically represented in hexadecimal format. Due to their length, IPv6 addresses can be written in different formats to make them more manageable.

Expanded Format

The expanded format of an IPv6 address consists of 8 groups of 4 hexadecimal digits, separated by colons. Each group represents 16 bits of the address.

Example: 2001:0db8:0000:0000:0000:0000:0000:0001

In this format, all leading zeros in each group are included, and no groups are omitted.

Compressed Format

The compressed format of an IPv6 address applies two rules to shorten the address:

  1. Leading zeros in each group can be omitted
  2. One or more consecutive groups of zeros can be replaced with a double colon (::)

Example: 2001:db8::1

Note: The double colon (::) can only appear once in an address to avoid ambiguity.

This is sometimes called “IPv6 compression” or “IPv6 shortening”.

Common IPv6 addresses

Description Compressed Expanded
Loopback ::1 0000:0000:0000:0000:0000:0000:0000:0001
Unspecified :: 0000:0000:0000:0000:0000:0000:0000:0000
IPv4-mapped ::ffff:192.168.1.1 0000:0000:0000:0000:0000:ffff:c0a8:0101
Link-local fe80::1 fe80:0000:0000:0000:0000:0000:0000:0001

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