Skip to main content
Digital, Internet & Technology

IPv6 Compression and Expansion Tool

Compress an IPv6 address to RFC 5952 canonical form, expand it fully, find its network prefix and address type.

Your inputs

Results

Compressed (RFC 5952)

2001:db8::1:0:0:1

Fully expanded
2001:0db8:0000:0000:0001:0000:0000:0001
Network prefix
2001:db8::/64
Address type
Documentation (2001:db8::/32)
Number of /64 subnets in this prefix
1

✓Exact calculation — rounded only for display

Notes for this result

  • Computed entirely in your browser; no address is sent anywhere.

What this calculator does

IPv6 addresses can be written many ways. RFC 5952 defines one canonical, lowercase, shortest form.

Formula and method

Remove leading zeros in each group; replace the longest run of two or more zero groups (the first if tied) with “::”.

Worked example

Calculated by this tool with its default inputs:

Inputs

  • IPv6 address (optionally with /prefix): 2001:0db8:0000:0000:0001:0000:0000:0001/64

Results

  • Compressed (RFC 5952): 2001:db8::1:0:0:1
  • Fully expanded: 2001:0db8:0000:0000:0001:0000:0000:0001
  • Network prefix: 2001:db8::/64
  • Address type: Documentation (2001:db8::/32)
  • Number of /64 subnets in this prefix: 1

How to read the results

A single zero group is never shortened to “::”.

Assumptions and limitations

  • Calculated entirely in your browser — addresses and values are never sent to a server.
  • Embedded IPv4 (e.g. ::ffff:192.0.2.1) is accepted.

Questions

Why lowercase?

RFC 5952 recommends lowercase hex for consistency.

Sources

Methodology and verification

Result type
Exact mathematical calculation (rounded only for display)
Formula version
1.0
Automated verification
7 reference and validation test cases, checked against independently computed values. The site cannot be built if any of them fail.
Editorial review
Awaiting human editorial review. The explanation was drafted with AI assistance; the formula and examples are verified by the automated tests above.

Privacy

Everything you enter is calculated in this browser and is not sent to Numerith or anyone else. Inputs are added to a share link only if you choose to include them. Privacy policy