Developer Tools
IPv6 Address Expander / Compressor - Full and Short IPv6 Notation
Expand an abbreviated IPv6 address to its full 8-group notation, or compress a full address to its canonical short form. Validates IPv6 syntax including embedded IPv4 addresses.
IPv6 Address Types
IPv6 addresses are 128-bit numbers usually written as eight groups of four hexadecimal digits
separated by colons. To keep addresses manageable, leading zeros in each group can be omitted
and consecutive all-zero groups can be replaced with ::.
IPv6 address types
| Type | Prefix | Description |
|---|---|---|
| Global unicast | 2000::/3 | Publicly routable addresses (like IPv4 public IPs) |
| Link-local | fe80::/10 | Auto-configured; only valid on local network segment |
| Loopback | ::1 | Equivalent to IPv4 127.0.0.1 |
| Multicast | ff00::/8 | One-to-many delivery to a group of hosts |
| Unique local | fc00::/7 | Privately routed (RFC 4193); similar to IPv4 10.x.x.x/172.16.x.x/192.168.x.x |
| Anycast | (any global unicast) | One address, multiple hosts; traffic goes to nearest |
IPv6 abbreviation rules
Two rules govern IPv6 address compression (RFC 5952):
- Omit leading zeros within each group:
0042->42;0000->0 - Replace one consecutive sequence of all-zero groups with
::. If multiple such sequences exist, only the longest may be compressed (ties: leftmost). Example:2001:0db8:0000:0000:0000:0000:0000:0001->2001:db8::1
IPv4 vs. IPv6
| Feature | IPv4 | IPv6 |
|---|---|---|
| Address size | 32 bits | 128 bits |
| Address space | ~4.3 billion | ~340 undecillion (3.4 × 10³⁸) |
| Notation | Dotted decimal (192.168.1.1) | Hex groups (2001:db8::1) |
| Address exhaustion | Exhausted (IANA: Feb 2011) | Effectively inexhaustible |
| NAT required | Yes (to extend address space) | No (every device gets a public address) |
When to Use Each Form
The expanded form is useful for debugging, routing tables, and when comparing addresses exactly. The compressed canonical form (per RFC 5952) is preferred for display and configuration files.