MAC Address Validator & Formatter
Check MAC addresses in any format and convert them to colon, hyphen, Cisco dotted or plain form, with unicast/multicast, local/universal bits and the IPv6 EUI-64 ID.
Vendor names are not looked up: that needs the full IEEE registry. Many phones and laptops now use randomised, locally administered addresses on Wi-Fi.
| Input | Valid | Formatted | Type | Administered | Notes |
|---|---|---|---|---|---|
| 00-1A-2B-3C-4D-5E | Yes | 00:1a:2b:3c:4d:5e | Unicast | universal | |
| f2:3c:91:aa:07:1b | Yes | f2:3c:91:aa:07:1b | Unicast | local | locally administered unicast — often a randomised (private) Wi-Fi address or a virtual interface |
| 0050.5689.ab12 | Yes | 00:50:56:89:ab:12 | Unicast | universal | VMware virtual NIC prefix |
| FF:FF:FF:FF:FF:FF | Yes | ff:ff:ff:ff:ff:ff | Broadcast | local | |
| 01:00:5E:00:00:FB | Yes | 01:00:5e:00:00:fb | IPv4 multicast (01:00:5e range) | universal | |
| ZZ:11:22:33:44:55 | No | — | — | — | contains characters that are not hexadecimal (0–9, A–F) |
MAC addresses turn up in many spellings — 00:1A:2B:3C:4D:5E on Linux, 00-1A-2B-3C-4D-5E on Windows, 001a.2b3c.4d5e on Cisco gear, or as twelve bare hex digits. Paste any mix, one per line, and this tool checks each one, rewrites it in the format you need and decodes the two flag bits of the first byte: unicast or multicast, and universally administered (a manufacturer's OUI) or locally administered. For a single address it also gives the modified EUI-64 interface ID and the IPv6 link-local address that SLAAC would form from it.
How to use this tool
- Paste one or more MAC addresses in any common format.
- Choose the output format and letter case.
- Read the formatted list and the table of types and flags.
- For one address, copy the EUI-64 interface ID or link-local address if you need it.
Formula
first byte: bit 0 (I/G) 0 = unicast, 1 = multicast · bit 1 (U/L) 0 = universal, 1 = local; EUI-64 ID = byte 1 XOR 02, bytes 2–3, FF FE, bytes 4–6
A MAC address is 48 bits written as 6 bytes. The first 3 bytes are the OUI the IEEE assigns to a manufacturer, unless the U/L bit marks the address as locally administered. IPv6 builds a 64-bit interface identifier by inserting FFFE in the middle and inverting the U/L bit (modified EUI-64, RFC 4291); with the fe80::/64 prefix that gives the link-local address.
Example
00-1A-2B-3C-4D-5E is valid and becomes 00:1a:2b:3c:4d:5e in colon form or 001a.2b3c.4d5e for Cisco. Its first byte 0x00 has both flag bits clear, so it is a universally administered unicast address. For EUI-64 the first byte becomes 0x02 and FF FE goes in the middle: 021a:2bff:fe3c:4d5e, so the link-local address is fe80::21a:2bff:fe3c:4d5e. ZZ:11:22:33:44:55 is invalid because Z is not a hex digit.
Frequently asked questions
Can this tell me the manufacturer?
Not reliably. Vendor names come from the IEEE registry of tens of thousands of OUIs, which this page does not download. It only recognises a few virtual-machine prefixes such as VMware 00:50:56 and VirtualBox 08:00:27.
Why does my phone show a different MAC on each Wi-Fi network?
Modern iOS, Android and Windows devices use private (randomised) addresses per network to limit tracking. They are locally administered, so the second hex digit is 2, 6, A or E.
Do devices still build IPv6 addresses from the MAC?
Link-local addresses on many routers and older systems do. Most current desktop and mobile systems use random or stable-privacy interface IDs (RFC 7217, RFC 8981) instead, so the EUI-64 form may not match what you see.
Sources
Last updated:
Page address with these inputs: https://kakao.mobile/tools/mac-address-validator/
Cite or embed this tool
kakaoCalc. (2026, November 8). MAC Address Validator & Formatter. https://kakao.mobile/tools/mac-address-validator/
“MAC Address Validator & Formatter.” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/mac-address-validator/.
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