MAC Address Formatter

A hardware address is the same 48 bits everywhere, but each platform writes it differently. Linux and macOS print colons, Windows prefers hyphens, Cisco IOS uses three dotted groups of four digits, and databases and some APIs want bare hex. When you copy addresses between a switch table, a DHCP server and a spreadsheet, the mismatch breaks lookups and makes duplicates invisible. The page converts a pasted list to the style you need.

The seven output styles

Pick an output format and the whole list is rewritten. aa:bb:cc:dd:ee:ff is the usual Linux and macOS style, in lower case; the same with capitals is common in documentation. AA-BB-CC-DD-EE-FF is the classic Windows getmac and ipconfig /all form, and the lower-case hyphen variant is used by some tools. aabb.ccdd.eeff is Cisco’s notation in show mac address-table. The unseparated forms aabbccddeeff and AABBCCDDEEFF suit databases and URLs. Quick buttons for Linux, Windows, Cisco and No separators set the style in one click.

What the parser accepts

Whatever the source used: colons, hyphens, dots, spaces, or no separator at all, in upper or lower case, and the less common 6-6 form 001a2b-3c4d5e that appears in some equipment menus. Each line is read separately, so lists that mix styles come out uniform. Exactly 12 hex digits make an address, so a value with more or fewer digits is not a valid 48-bit MAC address.

Why normalising matters

Equality tests on text are literal. An inventory that holds 00-1A-2B-3C-4D-5E will not match a switch log that prints 001a.2b3c.4d5e unless one side is converted. Sorting also changes with the notation, and an address with separators can fail a validation that expects bare hex. Converting everything once, at import, to a single canonical style avoids those errors. The case rule is the same: choose one.

A worked example

Take the address 00:1A:2B:3C:4D:5E. In Linux style it is 00:1a:2b:3c:4d:5e; in Windows style 00-1A-2B-3C-4D-5E; in Cisco style 001a.2b3c.4d5e; with no separators 001a2b3c4d5e. The first three bytes, 00:1A:2B, are the vendor prefix, and the MAC Address Lookup uses it to name the manufacturer. The sample list on the page contains one address in each notation so you can see them all unified in one step.

Limits

Only 48-bit EUI-48 addresses are handled. The 64-bit EUI-64 identifiers used by some radio technologies and by IPv6 interface identifiers are a different length; for the IPv6 relationship use the EUI-64 Calculator. The page changes spelling but does not check that an address is assigned, locally administered or in use.

Watch out for dropped zeros

Some commands print each byte without its leading zero. The arp command on macOS and BSD systems, for example, can show a byte 0x0a as a, giving an address such as 0:1a:2b:3c:4d:5e that has only eleven hex digits. An address like that is not a valid 48-bit value until each byte is padded to two digits, 00:1a:2b:3c:4d:5e. Pad the short bytes before pasting, and the page will convert the list to whichever notation your inventory, switch or DHCP server expects.

Related tools

• MAC Address Lookup names the vendor behind the prefix.
• MAC Address Generator creates random addresses in these styles.
• EUI-64 Calculator turns a MAC address into an IPv6 interface identifier.
• Wake-on-LAN Generator uses the address to build a magic packet.