IPv6 Compress Calculator

About this calculator

A fully expanded IPv6 address has eight groups of four hexadecimal digits separated by colons (e.g. 2001:0db8:0000:0000:0000:ff00:0042:8329), which is accurate but unwieldy to read or type. Compression shortens it in two steps defined by RFC 5952: first, leading zeros within each group are stripped (0db8 becomes db8, 0042 becomes 42), and second, the single longest run of one or more consecutive all-zero groups is collapsed into a double colon ::, which can appear at most once in a compressed address since two would make the number of omitted groups ambiguous.

Applying both rules to the example above gives 2001:db8::ff00:42:8329 — dramatically shorter and easier to work with, while still expanding back to exactly the same 128-bit address. Network engineers and system administrators rely on this canonical compressed form when writing configuration files, DNS records (AAAA), firewall rules, and documentation, since consistent compression avoids ambiguity between equivalent representations of the same address; this calculator takes a full 8-group IPv6 address and returns its compressed form.