Expanded: 2001:0db8:0000:0000:0000:0000:0000:0001 Compressed: 2001:db8::1 Integer: 42540766411282592856903984951653826561
About IPv6 Expand & Compress — Address Normalizer
IPv6 addresses can be written many different ways for the same value: a full address has eight groups of four hexadecimal digits, but leading zeros may be dropped and one run of all-zero groups can be collapsed to "::". That flexibility makes addresses readable, but it also makes them hard to compare by eye — "2001:db8::1" and "2001:0db8:0000:0000:0000:0000:0000:0001" are the same host.
This free IPv6 expand and compress tool normalizes an address both ways. Expand a shortened address into its full eight-group form to see every digit, or compress a full address into the canonical RFC 5952 short form for clean config files and logs. It also shows the 128-bit integer value.
Everything runs locally in your browser — addresses are parsed offline and nothing you paste is ever uploaded.
Features
- Expand abbreviated IPv6 into the full eight-group form
- Compress to canonical RFC 5952 short form (lowercase, leftmost longest :: run)
- Handles :: zero-groups and IPv4-in-IPv6 (e.g. ::ffff:192.0.2.1)
- Shows the 128-bit integer value; clear errors and fully offline
How to use
- Paste an IPv6 address into the input pane.
- Choose Expand for the full eight-group form, or Compress for the canonical short form.
- Read the expanded address, compressed address, and 128-bit integer in the output.
- Copy the result, or clear and try another address.
Frequently asked questions
What is the canonical (RFC 5952) form of an IPv6 address?
RFC 5952 defines a single recommended text form: use lowercase hex, drop leading zeros in each group, and collapse the longest run of consecutive all-zero groups (at least two) to "::", choosing the leftmost run on a tie. Following it means the same address always has the same string.
Why can an IPv6 address be written so many ways?
The format allows two abbreviations: leading zeros within a group may be omitted, and one run of zero groups may be replaced by "::". Both are optional, so a single address has many valid spellings. Expanding or compressing to one canonical form makes addresses comparable.
Can I use only one "::" in an address?
Yes — exactly one. The "::" stands in for "as many zero groups as needed to reach eight". If an address had two, the split would be ambiguous, so a second "::" is invalid and this tool reports an error.
How does IPv4-in-IPv6 (a dotted-quad ending) work?
An IPv6 address may end with an embedded IPv4 address, such as ::ffff:192.0.2.1. The four decimal octets map to the final two 16-bit groups. This tool accepts that trailing dotted-quad and expands it to the equivalent hex groups.
Does my IP address get sent anywhere?
No. All parsing and conversion happens locally in your browser. The address you paste never leaves your device, so it is safe to normalize internal or sensitive addresses.
Related tools
Everything runs locally in your browser — your input is never uploaded.