IPv6 Expander — Full Address Form

IPv6 addresses are usually written short — leading zeros dropped and a run of zero groups replaced by :: — which is convenient to type but awkward to compare, sort or paste into tools that expect a fixed width. This expander writes the address out in full as 8 groups of 4 hex digits, and also gives a compressed hex form, the address type, the reverse-DNS name and, if you add a /prefix, the network range.

How to use this tool

1. Paste an address such as 2001:db8::1. A /64 prefix, %zone or embedded IPv4 tail is fine.
2. Read the expanded form — always 39 characters.
3. Use the compressed form for documentation and configs.
4. Add more lines to expand a whole list at once.

Formula

missing groups = 8 − groups written · replace :: with that many 0000 groups · left-pad every group to 4 hex digits

An IPv6 address is 128 bits written as 8 groups of 16 bits. "::" may appear once and stands for one or more all-zero groups (RFC 4291). The compressed form follows RFC 5952: lowercase, no leading zeros, :: replaces the longest run of two or more zero groups (the first if tied), and is never used for a single group. Address-type labels describe recognized prefixes; they do not establish current allocation or reachability. The table shows up to 400 inputs.

Example

Take 2001:db8:85a3::8a2e:370:7334/64. Six groups are written, so :: stands for 8 − 6 = 2 zero groups, and the expanded address is 2001:0db8:85a3:0000:0000:8a2e:0370:7334. Because it sits inside 2001:db8::/32, the type is Documentation. The /64 network is 2001:db8:85a3::/64, running from 2001:0db8:85a3:0000:0000:0000:0000:0000 to 2001:0db8:85a3:0000:ffff:ffff:ffff:ffff — 18,446,744,073,709,551,616 addresses.