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IPv6 addresses can be written in either a fully expanded form (8 groups of 4 hex digits each) or a compressed shorthand form that collapses runs of zero groups — converting between the two by hand is tedious and error-prone. This tool converts any valid IPv6 address between its fully expanded and compressed forms.
How it works
Enter an IPv6 address and choose compress or expand. The tool parses the address into its 128-bit binary form, then reformats it either as 8 zero-padded groups (expand) or with the longest run of zero groups collapsed to "::" (compress).
- Enter iPv6 address.
- Enter mode.
- Click Calculate to see your results.
Examples
Compressing a fully expanded address
"2001:0db8:0000:0000:0000:0000:0000:0001" compresses to "2001:db8::1".
Who should use it
- Normalizing IPv6 addresses to a consistent format for configuration files or documentation.
- Expanding a compressed address to verify or compare it against a fully written reference address.
Industry applications
- Network engineering and systems administration
- Software development involving networking code
Advantages
- Handles both directions (compress and expand) in a single tool.
- Validates the address structure before converting, catching invalid input immediately.
Limitations
- Only handles standard IPv6 address notation, not embedded IPv4 or zone-index (%) suffixes.
Common mistakes to avoid
- Assuming any string of hex groups separated by colons is automatically valid IPv6 — the address must match the correct 128-bit structure.
- Manually padding or trimming zero groups instead of using the standard "::" compression rule.
Best practices
- Use the fully expanded form when you need to guarantee an unambiguous, directly comparable address string, such as in firewall rules or exact-match log filters.
Tips
- When documenting or troubleshooting network configurations, expanding addresses to their full form first can make it easier to spot subtle differences between similar-looking addresses.