IPv6 Expander

2001:0db8:0000:0000:0000:0000:0000:0001 · canonical 2001:db8::1

How it works

• Split the address on the `::` shorthand and padded the missing groups with zeroes.
• Padded each group to four hexadecimal digits for the expanded form.
• Compressed the longest run of zero groups and removed leading zeroes for the RFC 5952 canonical form.

• The `::` shorthand represents one or more zero groups; a valid IPv6 address has exactly eight groups when expanded.
• RFC 5952 requires a single `::` for the longest run of at least two zero groups and lower-case hexadecimal without leading zeroes.

Methodology

1. Expand any IPv4 tail to two hexadecimal groups.
2. Resolve `::` by padding missing groups with zeroes.
3. Pad each group to four digits for the expanded form, then apply the RFC 5952 compression rules for the canonical form.

Usage

1. Enter an IPv6 address in any accepted form.
2. Read the fully expanded 8-group form and the canonical form.

Examples

These are examples, not current values: they use fixed inputs, while the interactive tool computes live results in your browser.

Compressed address

{
  "address": "2001:db8::1"
}

Already explicit

{
  "address": "2001:0db8:0000:0000:0000:0000:0000:0001"
}

Loopback

{
  "address": "::1"
}

Limitations

Why IPv6 has two forms

An IPv6 address is 128 bits written as eight 16-bit hexadecimal groups. Because writing all eight is verbose, RFC 4291 allows a single `::` to stand for a run of zero groups and leading zeroes in a group to be dropped.

RFC 5952 then defines one canonical text form so that equal addresses always compare equal as strings. This tool shows both the fully expanded form and that canonical form.