MAC to IPv6 Link-Local Address: Modified EUI-64 Explained
Convert a 48-bit MAC address to a modified EUI-64 IPv6 interface identifier and understand why it cannot reveal a device's actual assigned IP address.
Use the related XKit tool
Open MAC To Ip ConverterA MAC address can be transformed into a modified EUI-64 interface identifier for an IPv6 link-local address. This is a deterministic conversion, not a network lookup: it cannot reveal a device's IPv4 address or confirm the IPv6 address currently assigned to it.
The modified EUI-64 steps
Start with the six bytes of a 48-bit MAC address. Insert FF:FE between the first three bytes and the last three bytes. Flip the universal/local bit of the first byte with an XOR of 0x02.
Group the resulting eight bytes into four IPv6 hexadecimal groups. Combine that interface identifier with the link-local prefix to form the candidate address.
Worked example: 00:1A:2B:3C:4D:5E
Inserting FF:FE produces 00:1A:2B:FF:FE:3C:4D:5E. Flipping the first byte changes 00 to 02, giving the interface identifier 021a:2bff:fe3c:4d5e.
The corresponding compressed link-local address is fe80::21a:2bff:fe3c:4d5e. Expanded and compressed IPv6 notations can describe the same address; compression removes leading zeros and a consecutive run of zero groups.
Why the generated address may not match your device
An operating system can use a different interface-identifier method, including stable or temporary privacy addresses. Therefore a calculated EUI-64 address is not proof that the device uses it.
IPv4 addresses are assigned separately and cannot be derived from a MAC address alone. Inspect the device's network settings or an authorized local network record to find its actual assigned address.
Sources and technical references
Frequently Asked Questions
Can a MAC address reveal an IPv4 address?
No. A MAC address does not encode its assigned IPv4 address. This tool performs an IPv6 identifier conversion, not a device or network lookup.
Will the generated IPv6 address always be the device's address?
No. The result assumes modified EUI-64 addressing. Devices can use other interface identifiers, so inspect actual network configuration to confirm an assigned address.