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MAC to IPv6 Converter

Turn a MAC address into the IPv6 link-local and SLAAC addresses an interface builds with EUI-64, or work backwards from an IPv6 address to the MAC inside it.

EUI-64 ADDRESSING

Convert MAC and IPv6

EUI-64
Colon, hyphen, Cisco dotted or bare hex, 12 digits.
Add the /64 your router or VPS provider assigned to get the global SLAAC address as well.

Nothing leaves your browser. The conversion is plain arithmetic done on this page; the MAC and prefix are never sent to VPSLake.

HOW TO USE IT

Convert in three steps

Handy when planning static neighbours, firewall rules or reverse DNS for IPv6 hosts.

  1. 1

    Enter the MAC address

    Copy it from ip link, Get-NetAdapter or your VPS panel. The link-local address appears as soon as the MAC is valid.

  2. 2

    Add the /64 prefix if you have one

    Use the prefix shown by ip -6 route or in your provider's network settings to get the global SLAAC address too.

  3. 3

    Copy the result, or go the other way

    Copy the addresses for your config or DNS. Switch to IPv6 to MAC to see which MAC an EUI-64 address was built from.

How modified EUI-64 works

The 48-bit MAC is split in half, FF:FE is inserted in the middle to make 64 bits, and the seventh bit of the first byte (the U/L bit) is flipped. So 52:54:00:12:34:56 becomes the interface ID 5054:ff:fe12:3456.

That 64-bit interface ID is appended to fe80::/64 for the link-local address, and to any /64 prefix the router advertises for the global address.

Why many hosts no longer use it

An address that embeds the MAC follows a device across networks, so modern systems prefer privacy addresses (RFC 4941) or stable-privacy IDs (RFC 7217). Windows, macOS, iOS, Android and NetworkManager-based Linux usually do this by default.

Routers, switches, embedded devices and many server images still use EUI-64, so the calculation is still useful for planning and auditing.

IPv6 on a VPS

Most providers route a /64 to each VPS and expect a static address inside it rather than SLAAC. Even so, the link-local address shown here is what the host uses for neighbour discovery with its gateway, which helps when you read ip -6 neigh or debug a missing default route.

Recognising an EUI-64 address

Look at the last 64 bits: if the middle reads ff:fe, as in …:5054:ff:fe12:3456, the address was almost certainly built from a MAC. The reverse tab undoes the steps and returns the original MAC, which you can then run through the MAC address lookup.

Check the real address before relying on it

The result is what EUI-64 would produce. A host using privacy or stable-privacy addressing, or a static configuration, will have a different address. Confirm with ip -6 addr or ipconfig on the machine before you put an address in a firewall rule or DNS record.

FREQUENTLY ASKED QUESTIONS

MAC to IPv6 FAQ

In a MAC address that bit means "locally administered". RFC 4291 inverts it in the interface ID so that ordinary factory MACs produce IDs with the bit set to 1, leaving simple hand-written IDs like ::1 with it set to 0.
SLAAC and EUI-64 always fill the last 64 bits with the interface ID, so the network part has to be exactly 64 bits. Longer or shorter prefixes need static or DHCPv6 addressing instead.
The host is probably using privacy extensions, a stable-privacy ID, DHCPv6 or a static address. Only the link-local address is reliably EUI-64 on many Linux servers, and even that can be stable-privacy on newer distributions.
No. Only addresses whose interface ID has FF:FE in the middle were built with EUI-64. Random, privacy, DHCPv6 and manually set addresses contain no MAC, and the tool says so instead of guessing.
No. All the arithmetic runs in JavaScript on this page. Nothing is uploaded, logged or stored by VPSLake.
A MAC with an odd first byte is a group address that no interface uses as its own, so it never produces a real interface ID. The tool still shows the arithmetic but warns you.