🏷️ MAC Address Formatter
Paste a MAC in any format and get every standard notation — colon, hyphen, Cisco dotted, bare hex — plus its EUI-64 form and IPv6 link-local address.
| Colon (Unix / macOS) | aa:bb:cc:dd:ee:ff | |
|---|---|---|
| Hyphen (Windows) | aa-bb-cc-dd-ee-ff | |
| Dotted (Cisco IOS) | aabb.ccdd.eeff | |
| Bare hex | aabbccddeeff | |
| EUI-64 interface ID | a8:bb:cc:ff:fe:dd:ee:ff | |
| IPv6 link-local | fe80::a8bb:ccff:fedd:eeff |
EUI-64 flips the universal/local bit and inserts ff:fe; the link-local address is fe80::/64 + EUI-64. Everything is computed locally — MAC addresses identify hardware, so they never leave your browser here.
How the mac address formatter works
Every vendor writes MAC addresses differently: Linux and macOS use colons (aa:bb:cc:dd:ee:ff), Windows uses hyphens (AA-BB-CC-DD-EE-FF), Cisco IOS uses dotted quads (aabb.ccdd.eeff), and databases often store bare hex. The formatter parses any of them and emits all four, in your choice of case — the everyday job when moving addresses between a switch console, a DHCP reservation form and a spreadsheet. It also computes the modified EUI-64 interface identifier (split the MAC, insert ff:fe, flip the universal/local bit) and from it the IPv6 link-local address (fe80::/64 + EUI-64) — which is how you can predict a device’s link-local IPv6 address from the MAC printed on its label.
The U/L bit flip is the step everyone forgets when deriving EUI-64 by hand: the second-least-significant bit of the first byte inverts, so a MAC starting aa: gives an EUI-64 starting a8:. Note that modern client OSes use random privacy addresses instead of EUI-64 for their routable IPv6 — but link-local EUI-64 derivation still works on most routers, switches and embedded gear.
Frequently asked questions
Which MAC formats exist?
Four are common: colon-separated pairs (Unix), hyphen-separated pairs (Windows), Cisco’s three dotted groups of four, and bare 12-digit hex. All encode the same 48 bits.
What is EUI-64?
A 64-bit interface identifier derived from the 48-bit MAC: split it in half, insert ff:fe in the middle, and flip the universal/local bit of the first byte. IPv6 uses it to build interface IDs.
How is the IPv6 link-local address derived from a MAC?
Prefix fe80::/64 plus the EUI-64 interface identifier. For MAC aa:bb:cc:dd:ee:ff that gives fe80::a8bb:ccff:fedd:eeff — predictable from the label on the device.
Why doesn’t my laptop’s IPv6 address match its MAC?
Modern operating systems use randomized (privacy) interface identifiers rather than EUI-64 for exactly that reason — MAC-derived addresses would let websites track hardware. Routers and embedded devices still commonly use EUI-64.
Is the MAC I paste sent anywhere?
No — formatting happens locally. MAC addresses identify your hardware, so they’re not something to feed into random online tools that log requests.