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📐 IPv6 Expand / Compress
IPv6 addresses can be written several ways. Shortest form drops leading zeros in each group and replaces a run of zero groups with double-colon. Expanded form spells every nibble out. This tool toggles between them and also detects IPv4-mapped addresses like ::ffff:192.168.1.1.
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Examples
Compress to expand
Input
2001:db8::1Output
2001:0db8:0000:0000:0000:0000:0000:0001Frequently asked questions
Can :: appear twice?
No. RFC 5952 allows :: only once — otherwise the address would be ambiguous about where the zeros go.
About this calculator
IPv6 Expand / Compress runs entirely in your browser using standard formulas. No data is sent to any server. We don't share your inputs with lenders, brokers, or anyone else — there's no funnel and no follow-up email.
Related tools
- 🔢 IPv4 ↔ Binary / Hex / Decimal — Convert IPv4 between dotted decimal, binary, hex, and integer.
- 🧮 Subnet / CIDR Calculator — Calculate network, broadcast, host range, mask from any CIDR notation.
Why this tool
vs typical free network-tools sites
| NetToolset | Typical free site | |
|---|---|---|
| Price | Free | Free |
| Signup required | No | Often (for advanced features) |
| Ads inside the tool | No | Yes (banner + interstitial) |
| Logs your IP / queries | No | Yes (often resold) |
| Data sent to a server | Math runs in browser; lookups hit Cloudflare DoH directly | Yes (all goes through their server) |
| Open source | Yes | No |
| Bookmarkable URL per tool | Yes | Mixed |
| Multilingual | EN / ES / PT / FR / DE | Usually EN only |
| Loads in under 1s | Yes (static) | Often slow (ad tracking) |