About IPv6 expand/compress
This tool expands a shortened IPv6 address to its full eight-group form, and compresses a full address to the shortest valid form. It normalises addresses so you can compare them reliably across configs and logs.
How IPv6 Expander works
How to use it
- Enter an IPv6 address in any valid form.
- Read both the expanded and compressed versions.
How it works
Expanding restores the :: shorthand to the missing zero groups and pads each group to four digits. Compressing removes leading zeros and replaces the longest run of zero groups with ::, which is the canonical short form.
Common uses
- Expand a short IPv6 address
- Compress a full IPv6 address
- Normalise IPv6 for comparison
- Match addresses in logs
- Validate an IPv6 address
- Study IPv6 notation
- Clean up firewall rules
- Teach IPv6 addressing
Frequently asked questions
What does :: mean in IPv6?
It is shorthand for one or more groups of all-zero, used once per address.
How do I expand an IPv6 address?
Enter it and the full eight-group form is shown.
How is it compressed?
Leading zeros are removed and the longest zero run becomes ::.
Is my address uploaded?
No — it runs in your browser.
How many groups does IPv6 have?
Eight groups of four hex digits.
Why normalise addresses?
So the same address always looks identical when compared.
Does it validate input?
Yes — invalid addresses are flagged.
Is it free?
Yes — completely free with no sign-up.