IPv6 Expansion Calculator
Expand a compressed IPv6 address into all eight 16-bit groups with leading zeros restored.
Inputs
Expanded Address
2001:0db8:0000:0000:0000:ff00:0042:8329
Compressed Address
2001:db8::ff00:42:8329
Hex Digits
32
16-bit Groups
8
Step by step
Values used
IPv6 address = 2001:db8::ff00:42:8329
IPv6 Expansion
'::' is replaced by as many '0000' groups as are needed to reach eight groups, then every group is padded to four hex digits.
Expanded Address
= 2001:0db8:0000:0000:0000:ff00:0042:8329
Compressed Address
= 2001:db8::ff00:42:8329
Hex Digits
= 32
16-bit Groups
= 8
How it works
Expansion counts the groups either side of '::', inserts the missing zero groups, and pads each group to four digits — the form most parsers, regexes and hardware tables expect. Fixed-width addresses sort correctly, match reliably in regular expressions, and line up when you are eyeballing prefix boundaries in a capture.
Formula
IPv6 Expansion
'::' is replaced by as many '0000' groups as are needed to reach eight groups, then every group is padded to four hex digits.
- ::
- Compressed run of zero groups being restored
Frequently Asked Questions
How is IPv6 Expansion calculated?
'::' is replaced by as many '0000' groups as are needed to reach eight groups, then every group is padded to four hex digits. Expansion counts the groups either side of '::', inserts the missing zero groups, and pads each group to four digits — the form most parsers, regexes and hardware tables expect.
Why does IPv6 Expansion matter?
Fixed-width addresses sort correctly, match reliably in regular expressions, and line up when you are eyeballing prefix boundaries in a capture.
What values do I need to enter?
This calculator takes 1 input: IPv6 address. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.