Free tool
NetworkingIPv6 to EUI-64 Converter
Free IPv6 to EUI-64 calculator. Convert a MAC address to modified EUI-64, build the fe80:: link-local address, or pull the interface ID out of an IPv6 address, CCNA-friendly and runs in your browser.
Runs in your browser — your data stays on your device
Free toolIPv6 often builds the host half of an address from the interface MAC using modified EUI-64. This free IPv6 to EUI-64 calculator does that conversion for you: paste a MAC and get the 64-bit interface ID, the fe80:: link-local address, and if you want, a full address on a /64 prefix. You can also paste an IPv6 address the other way and extract the EUI-64 interface identifier (and reverse it back to a MAC when the classic FF:FE pattern is there).
How to use the IPv6 EUI-64 calculator
- 1
Enter a 48-bit MAC address in any common format (colons, hyphens, or Cisco dotted style), or paste a full IPv6 address if you want to read the interface ID out of it.
- 2
For MAC mode, the tool inserts FF:FE, flips the U/L bit, and shows the modified EUI-64 plus the link-local fe80:: address.
- 3
Optional: tick the /64 prefix box and enter something like 2001:db8:1:2:: to build a global IPv6 address the same way SLAAC would with EUI-64.
Why EUI-64 still shows up in CCNA and real labs
Stateless Address Autoconfiguration (SLAAC) historically formed the interface identifier from the MAC using modified EUI-64. Even though many hosts now prefer privacy extensions with random interface IDs, exams and textbooks still expect you to split the MAC, drop FF:FE in the middle, and invert the seventh bit. Doing it by hand is fiddly; this calculator lets you check your working in seconds while you learn the steps.
Worked example, MAC to EUI-64 to link-local
Take MAC 00:1B:44:11:3A:B7. Split it into 00:1B:44 and 11:3A:B7, insert FF:FE → 00:1B:44:FF:FE:11:3A:B7, then flip the U/L bit so the first octet 00 becomes 02. The modified EUI-64 interface ID is 021b:44ff:fe11:3ab7, and the link-local address is fe80::21b:44ff:fe11:3ab7. Paste that IPv6 back into the tool and it will pull the same interface ID out, and recover the original MAC when FF:FE is present.
Guides and next steps
Privacy note
MAC and IPv6 conversions run entirely in your browser. Nothing you enter is uploaded or stored on our servers.
Frequently asked questions
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