MAC Address Lookup

Look up the manufacturer and organization associated with a MAC address OUI prefix from a local database.

Tested tool guide Tested browser tools Checked August 16, 2026

What MAC Address Lookup does and how it behaves

MAC Address Lookup identifies the registry organization associated with the OUI portion of a hardware address. Enter a MAC address, and the tool compares its leading prefix with its local assignment database, then reports the matching manufacturer or organization record. The lookup stays in the browser, so the address is not sent to a remote lookup service. The common surprise is that an OUI identifies the organization assigned a prefix, not necessarily the company shown on the device, its exact model, its owner, or its physical location. Randomized or locally administered addresses may have no useful vendor attribution.

How the result is produced

Prefix matching

The lookup key is the address's leading registered prefix. In the traditional OUI case, that prefix is 24 bits, usually displayed as the first three octets, such as AA:BB:CC. The tool checks that prefix against its local records and returns the associated organization when a record exists. The remaining octets do not change the result of a 24-bit OUI lookup.

Address-bit interpretation

MAC address bits affect whether registry attribution is meaningful. In the first octet, the Individual/Group bit distinguishes individual from group addressing, while the Universal/Local bit distinguishes universally administered from locally administered addresses. A locally administered value can be generated by an operating system or network policy, so a matching-looking prefix is not proof that the named organization made the device.

Good uses

During a switch-port or DHCP inventory, check an unfamiliar client address for the organization associated with its registered prefix. This can provide an initial vendor clue before examining hostnames, authentication records, or the physical device.
While reviewing a packet capture, look up an unknown source or destination MAC address to see whether its prefix points to a network-interface, computer, phone, printer, or embedded-device vendor worth investigating.
When reconciling asset records, verify whether the prefix recorded for a device corresponds to the expected supplier. A disagreement can reveal a replaced adapter, virtual interface, copied address, randomized address, or incorrect inventory entry.

Limits and checks

A locally administered or privacy-randomized address does not reliably identify its hardware manufacturer. Check the Universal/Local bit before treating an organization name as evidence about the physical interface.
The returned organization is the registered prefix assignee. It is not necessarily the product brand, contract manufacturer, device operator, network owner, current corporate parent, or organization responsible for traffic from that address.
A local database is a snapshot. A missing or outdated result can reflect registry changes or an assignment absent from that snapshot. Also, not every IEEE address allocation has the same prefix length, so a simple 24-bit OUI result may be less specific than the available assignment.

Common questions

Can this lookup identify the exact device or its owner?

No. A registry prefix can suggest the organization that received an address block, but it does not encode a product model, serial number, person, account, or location. The device-specific portion is assigned within that block. Shared prefixes, replacement adapters, virtual machines, address spoofing, and privacy randomization make exact identification impossible from this result alone.

Why does a valid MAC address return no organization?

The address may be locally administered, randomized, derived for a protocol-specific purpose, or absent from the tool's local database. It may also belong to an assignment represented at a different prefix length. A syntactically valid MAC address is therefore not guaranteed to have a manufacturer result, and no match does not by itself mean the address is invalid.

References and verification

The behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.