🏷️ 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.