MAC Address Generator

Generate random MAC addresses with optional OUI prefix in colon, hyphen, or dot notation formats.

MAC Address Generator tool

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Example

Input: Format Colon, Uppercase, Count 1, Unicast and Locally administered on, then Generate

Result: One random address in the form XX:XX:XX:XX:XX:XX whose first byte ends in binary 10 (for example 02, 76, AE or F6)

The lowest bit of the first byte is 0 for unicast and the next bit is 1 for locally administered, so the address cannot clash with a vendor-assigned MAC. A new address is generated on every click.

What the First Byte of a MAC Address Means

Address typeLast 2 bits of byte 1Second hex digit
Unicast, locally administered102, 6, A, E
Unicast, universally administered000, 4, 8, C
Multicast, locally administered113, 7, B, F
Multicast, universally administered011, 5, 9, D

The generator default is the first row.

  1. Pick a format: colon (AA:BB:CC:DD:EE:FF), hyphen, Cisco dot or no separator, and choose upper or lower case.
  2. Optionally enter an OUI prefix (up to the first 3 bytes) to imitate a specific manufacturer.
  3. Set the Unicast and Locally administered toggles. They apply only when no OUI prefix is entered.
  4. Enter how many addresses you need, from 1 to 100.
  5. Click "Generate", then copy single addresses or use "Copy All" for the whole list.

Random MAC Addresses for Testing and VMs

This tool makes random 48-bit MAC addresses for labs, virtual machines, test data and documentation. By default each address is unicast and locally administered, so the last two bits of its first byte are 10 and it can never match an address a manufacturer burned into real hardware. You can create up to 100 at a time.

A MAC address is the hardware address a network card uses on the local network. It has six bytes, and the first byte holds two flag bits. Bit 0 says unicast (one device) or multicast (a group). Bit 1 says universally administered (set by the maker) or locally administered (set by you or your software). The two toggles control these bits, and the table below shows which second hex digit each choice produces.

If you need addresses that look like a real brand, enter an OUI prefix, the vendor part in the first three bytes. For example, 00:50:56 is registered to VMware. The tool copies the whole bytes you give it and fills the rest at random. The two toggles are then ignored, because the OUI already sets both bits. Borrowing a real vendor prefix can clash with genuine hardware on the same network, so keep it to test setups.

Pick colon (AA:BB:CC:DD:EE:FF), hyphen, Cisco dot (AABB.CCDD.EEFF) or no separator, in upper or lower case. The random bytes come from the crypto API in your browser. To check which company owns a prefix, paste it into the MAC Address Lookup.

Sources

Frequently Asked Questions

The second-lowest bit of the first byte is set to 1. In hex, that means the second digit of the address is 2, 3, 6, 7, A, B, E or F. For unicast addresses, which normal devices use, only 2, 6, A and E appear, as in 02:xx or AE:xx. Locally administered addresses are meant for VMs, containers and devices that randomize their MAC.
A unicast, locally administered address is the safe choice, and it is the default here. It cannot collide with any vendor-assigned network card. Hypervisors such as VMware, Hyper-V and VirtualBox also create MACs under their own vendor prefixes, and some only accept manual addresses inside a set range, so check your platform documentation before you set one by hand.
A unicast address points to one network interface. A multicast address has the lowest bit of the first byte set to 1 and is delivered to every device listening for that group. Normal network cards always use unicast addresses, so leave the Unicast toggle on unless you are testing how software handles multicast.
They should not share one on the same local network, because switches would not know where to send frames. Random addresses rarely collide: with the two flag bits fixed there are still 46 random bits, about 70 trillion choices. Duplicates on separate networks do not matter, since MAC addresses are not passed on past the local segment.

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