IPv6 Address Converter
Expand or compress any IPv6 address and see it as binary, decimal, hex groups and an ip6.arpa reverse DNS name – or turn a decimal number back into IPv6.
The same IPv6 address can be written many ways – full, shortened, with or without leading zeros. This converter gives you the canonical RFC 5952 form plus every representation you need while troubleshooting: expanded, binary, decimal, hex, the /64 network and interface ID, the EUI-64 MAC (when present) and the ip6.arpa name for reverse DNS.
How to use it
- Paste an address – any format, with or without a
%zonesuch as%eth0. - Or paste a decimal number (up to 2^128 − 1) to convert it back into an IPv6 address.
- Copy the form you need: compressed for documentation and DNS, expanded for firewall exports, the PTR name for reverse zones.
When you’ll need it
- Matching log entries – one system logs
2001:db8::1, another2001:0db8:0000:…:0001. - Creating PTR records for a mail server (receivers check reverse DNS).
- Spotting SLAAC addresses that reveal a device’s MAC (EUI-64).
Frequently asked questions
What are the rules for shortening an IPv6 address?
RFC 5952: drop leading zeros in each group, replace the longest run of two or more all-zero groups with “::” (only once), and write hex letters in lower case.
What is the ip6.arpa name for?
Reverse DNS (PTR records) for IPv6 uses every hex digit, reversed and separated by dots, under ip6.arpa. Mail servers need a matching PTR record to be trusted.
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