MAC Address Generator and Formatter
Generate random MAC addresses or reformat and inspect existing ones.
Use via API
Generate random MAC addresses (locally administered unicast by default, optional vendor OUI prefix), or inspect and reformat an existing one. Send JSON, get JSON back.
POST https://pithlab.com/api/v1/tools/mac-address-generator
curl https://pithlab.com/api/v1/tools/mac-address-generator \
-H "Authorization: Bearer $PITHLAB_KEY" \
-H "Content-Type: application/json" \
-d '{"count":3,"format":"colon"}'About the MAC Address Generator
Generate random MAC addresses in bulk, with an optional fixed OUI, or normalise pasted MACs to colon, hyphen or Cisco dot format and check their U/L and I/G bits.
How to use the MAC Address Generator
- In Generate mode, choose how many addresses you need, from 1 to 1,000, and the output format and case.
- Keep Locally administered ticked for addresses that can never clash with a real vendor's hardware, or enter a fixed OUI such as 00:1a:2b to use a vendor prefix.
- Press Generate, then copy the list or download it as a text file.
- In Format mode, paste MAC addresses one per line to convert them to the chosen format and see whether each is unicast or multicast, and universal or local.
Examples
Input
1 address, colon format
Output
e.g. 02:5f:c3:9a:11:e7
Input
OUI 00:1a:2b, Cisco dot
Output
e.g. 001a.2b4c.d8f0
Input
00-1A-2B-3C-4D-5E
Output
00:1a:2b:3c:4d:5e: unicast, universally administered (vendor OUI)
Input
0100.5e00.00fb
Output
01:00:5e:00:00:fb: multicast, universally administered (vendor OUI)
Frequently asked questions
What does locally administered mean?
The second-lowest bit of the first byte is the U/L bit. When it is set, the address was assigned locally rather than burned in by a manufacturer, so it cannot collide with a real vendor address. Locally administered unicast addresses have 2, 6, a or e as the second hex digit.
What is the I/G (multicast) bit?
The lowest bit of the first byte marks an individual (unicast) address when clear and a group (multicast) address when set. Network cards should use unicast addresses, so leave multicast off unless you are testing group traffic.
What happens when I set a fixed OUI?
The first three bytes are taken exactly as you entered them and only the last three are random. The unicast and locally administered options are not applied, because they would change your prefix.
How random are the addresses?
Bytes come from the browser's cryptographically secure random generator. Each address has 46 random bits by default, so duplicates in a list of 1,000 are extremely unlikely, though not impossible.
Which input formats does the formatter accept?
Colon or hyphen separated pairs (single digits such as 0:1a:2b are padded), Cisco dotted groups of four, and 12 hex digits with no separator. Upper and lower case both work.