IPv6 Address Expander & Compressor
Expand and compress IPv6 addresses. Convert between full notation and shorthand ::, validate, and get reverse DNS, URL-literal, and binary forms.
About this tool
An IPv6 address has 128 bits, written as eight groups of four hexadecimal digits separated by colons (e.g. 2001:0db8:0000:0000:0000:0000:0000:0001). RFC 5952 lets you drop leading zeros and replace one consecutive run of zero-groups with ::, giving the compressed form 2001:db8::1. This tool converts between the two forms, validates the address, and shows extra representations developers need when configuring DNS, firewalls, and network utilities.
What it produces:
- Expanded form — all 8 hextets, 4 hex digits each. Useful for configuring firewalls, ACLs, and
ip6tablesrules where you need the full address. - Compressed form — the shortest valid notation with
::. Useful for URLs and config files. - Reverse DNS — the
.ip6.arpaPTR record name used in DNS lookups. - URL literal — bracketed form
[2001:db8::1]required in URLs per RFC 3986. - Binary — the 128 bits grouped by hextet, useful for subnet calculations.
- Scope & type — detects loopback, link-local, ULA, multicast, IPv4-mapped, global unicast, and more.
Examples:
2001:db8::1expands to2001:0db8:0000:0000:0000:0000:0000:0001::ffff:192.168.1.1is detected as IPv4-mapped, representing IPv4192.168.1.1fe80::1is classified as link-local (single-network scope)
FAQ
What is the difference between expanded and compressed IPv6 notation? ›
Expanded notation writes all 8 hextets with 4 hex digits each (2001:0db8:0000:0000:0000:0000:0000:0001). Compressed notation removes leading zeros within each hextet and replaces the longest run of all-zero hextets with ::, giving 2001:db8::1. Both forms are valid; compressed is preferred for human readability, expanded is useful for tools and documentation.
Does this tool support zone IDs (like fe80::1%eth0)? ›
Yes. Zone IDs (also called scope IDs or interface indices) are parsed and preserved in the compressed and URL-literal outputs. They identify which network interface a link-local address belongs to, which is required on multi-interface systems.
Can it handle IPv4-mapped addresses like ::ffff:192.168.1.1? ›
Yes. The embedded IPv4 address is parsed into two hextets and the tool detects the ::ffff:0:0/96 prefix, labeling the result as IPv4-mapped. It also handles the deprecated IPv4-compatible format (::192.168.1.1).
How does the reverse DNS (.ip6.arpa) name get calculated? ›
Each nibble (half-hextet) of the 128-bit address is reversed and appended with .ip6.arpa. For example, 2001:db8::1 produces 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa. This is the name used in PTR records for reverse DNS lookups.