How to use the mac address formatter
- Paste MAC addresses, one per line, in any common layout: colons, hyphens, dots or no separators.
- Choose the style: colons (aa:bb:cc), hyphens (aa-bb-cc), dots (aabb.ccdd.eeff) or no separators.
- Choose lowercase or uppercase letters.
- Read the reformatted list and the table of each address with its first three octets, its unicast or multicast type and its administration. Lines that are not MAC addresses are named in the notes.
What a MAC address is
A MAC address identifies a network interface, such as a Wi-Fi or Ethernet adapter. It is 48 bits, written as 12 hexadecimal digits. Different systems write it differently: Linux and many tools use colons, Windows often uses hyphens, Cisco gear uses three groups of four digits separated by dots, and some software wants the bare 12 digits. The address is the same in all of them, so converting is a matter of layout.
The page accepts 12 digits grouped by colons, by hyphens, by dots in groups of four, with spaces between pairs, or all together. Mixed separators, wrong lengths and characters that are not hex digits are refused with the line number, so a typo does not slip through.
Reading the first octet
The first octet carries two flags. Its lowest bit tells you whether the address is unicast, meant for one device, or multicast, meant for a group. Its next bit tells you whether the address was assigned by the maker of the hardware, which is universally administered, or set by software, which is locally administered. For 01:00:5e:00:00:fb the first octet is 01, so it is multicast. For 02:42:ac:11:00:02 the first octet is 02, so it is locally administered, as are addresses made by virtual machines, containers and many phones that randomize their address.
The first three octets are the vendor part for universally administered addresses. The table shows them in hyphen form so you can look them up in a registry, and the page does not look vendors up itself. A simple sample, 00:1A:2B:3C:4D:5E, becomes 001A.2B3C.4D5E in dot style with uppercase letters, 00-1A-2B-3C-4D-5E with hyphens and 001a2b3c4d5e with no separators.
Related tools and privacy
For IP addresses, the IP Address Format Converter changes between dotted, hex and integer forms, and the Subnet Calculator works out network ranges. The Number Base Converter turns the hex digits into binary or decimal, and the Hex Viewer shows the bytes of a file. Everything runs in your browser, and the addresses are never uploaded.
Assumptions and limits
- An address is exactly 12 hex digits, in one separator style per address.
- The unicast, multicast and administration flags come from the first octet only.
- Vendor names are not looked up. Up to 200,000 characters are read.
- Nothing is uploaded or stored.
Frequently asked questions
How do I convert a MAC address from colons to hyphens?
Paste the address, choose the hyphen style, and the page rewrites it. 00:1a:2b:3c:4d:5e becomes 00-1a-2b-3c-4d-5e, in lowercase or uppercase as you choose.
What is the dot format for a MAC address?
It writes the 12 digits as three groups of four, separated by dots, such as 001a.2b3c.4d5e. It is the layout used on Cisco equipment.
What does locally administered mean?
The address was set by software rather than by the hardware maker. It is marked by the second lowest bit of the first octet. Virtual machines, containers and phones that randomize addresses use such addresses.
Does it tell me the manufacturer?
No. It shows the first three octets so that you can look them up in a registry, but it does not look vendors up or send anything over the network.