IPv6 notation tool

Expand IPv6 address 21:bd:154::549:1

Write any valid IPv6 address in its complete eight-group form for subnetting, binary analysis, logs, and documentation.

Example: 2001:db8::1

The conversion runs locally and does not use an external lookup service.

Expansion result

Full IPv6 notation for 21:bd:154::549:1

Expanded IPv6 address

0021:00bd:0154:0000:0000:0000:0549:0001

Compressed IPv6

21:bd:154::549:1

Expanded IPv6

0021:00bd:0154:0000:0000:0000:0549:0001

IPv6 groups

8 groups of 4 hexadecimal digits

Address size

128 bits

Expansion rules

How IPv6 expansion works

  1. 1An IPv6 address always has eight 16-bit hexadecimal groups.
  2. 2Each visible group is left-padded with zeroes until it contains four digits.
  3. 3If :: appears, it is replaced with the number of 0000 groups needed to reach eight groups.

Binary representation

128 bits, grouped for inspection

Each block below represents one 16-bit IPv6 group. This form is useful when comparing prefix bits or troubleshooting subnet boundaries.

0000000000100001 0000000010111101 0000000101010100 0000000000000000 0000000000000000 0000000000000000 0000010101001001 0000000000000001
Compress this IPv6 address

Recent notation conversions

Recent IPv6 Expansions

Open recent IPv6 addresses to inspect their complete eight-group and binary forms.

Learn how IPv6 expansion and binary groups work