Turn a MAC address into its EUI-64 interface ID and fe80:: address, and back again
Runs in your browser. Nothing you type is sent anywhere. Checked against sources on 17 Oct 2026.An IPv6 host using SLAAC without privacy extensions builds its interface ID from its MAC: FF-FE goes in the middle and the seventh bit of the first byte is flipped. Paste a MAC such as 00:00:5E:00:53:01 to get fe80::200:5eff:fe00:5301, add your /64 prefix for the global address, or paste an IPv6 address to recover the MAC it was made from.
Type the domain, host name or IP address.
Press Check. The question goes only to the public service named next to the box.
Read the verdict and the records, then copy them.
Every network tool prints MAC addresses its own way: Linux and macOS use colons, Windows uses hyphens, Cisco switches group four digits with dots, and databases often store 12 bare digits. Paste any of them, or an 8-byte EUI-64, and get all the others at once, in capitals or small letters.
A second hex digit of 2, 6, A or E means a locally administered unicast address, as used by virtual machines, Docker and phones that randomise their MAC per network. The page also names the special blocks: broadcast FF-FF-FF-FF-FF-FF, 01-00-5E IPv4 multicast, 33-33 IPv6 multicast, and IANA's 00-00-5E range with its documentation addresses.
IPv6 from a MAC. Without privacy extensions, an IPv6 host builds its interface identifier from its MAC by RFC 4291 Appendix A: insert FF-FE between the third and fourth bytes and flip the Local bit. So 00:00:5E:00:53:01 becomes 0200:5eff:fe00:5301, and the link-local address is fe80::200:5eff:fe00:5301. Add your /64 prefix for the global address, or paste an IPv6 address to read back the MAC inside it.
The rest of the article, and all 6 questions about MAC Address Converter, are on the MAC Address Converter page.
RFC 4291 inserts FF-FE between the third and fourth bytes of the MAC and flips the second-lowest bit of the first byte, giving a 64-bit interface identifier. The link-local address is fe80:: followed by it, so 00:00:5E:00:53:01 becomes fe80::200:5eff:fe00:5301.
A MAC whose first byte has the 02 bit set, which makes the second hex digit 2, 6, A or E. Software assigned it rather than the manufacturer: virtual machines, containers, bonded interfaces and phones that randomise their address per Wi-Fi network all use such addresses.
Look at the lowest bit of the first byte: when it is 1, the second hex digit is odd and the address is a group address that many devices listen to. 01-00-5E addresses carry IPv4 multicast, 33-33 addresses carry IPv6 multicast, and FF-FF-FF-FF-FF-FF is the broadcast address.
Yes, when the address was built from a MAC without privacy extensions: its interface identifier then has ff:fe in the middle, as in fe80::200:5eff:fe00:5301. Paste the address and the MAC is rebuilt. Random privacy and stable-privacy addresses contain no MAC, and the page says so.
Rates and rules change; check the source before you rely on a figure.
Still stuck? Ask about MAC Address Converter and anybody who knows can answer. No account needed.
Same job, other tools: AAAA Record Lookup (IPv6) – Check whether a domain has an IPv6 address, and what it is · IP to ASN Lookup – Map an IP address to the ASN that announces it, with the BGP prefix · IP WHOIS Lookup – Who holds an IP address: network name, range, organisation and country as registered.