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MAC Address Tool

EUI-48
Format Conversion
Enter a MAC address above to see format conversions
MAC Address Properties
Enter a MAC address above to see its properties
EUI-48 → EUI-64 Conversion

Expands a 48-bit MAC (EUI-48) to a 64-bit EUI-64 identifier used in IPv6 interface IDs. The process inserts FF:FE between bytes 3 and 4, then flips bit 6 (U/L bit) of the first byte.

Enter a MAC address above to convert to EUI-64
Random MAC Generator
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Batch MAC Validator

Paste one MAC address per line. Accepts colon, hyphen, dot (Cisco), or no-separator formats.

OUI Vendor Database
OUI PrefixVendor

What is MAC Address Lookup Tool?

MAC Address Lookup Tool identifies the manufacturer of a network device from its MAC address. Enter a MAC address in any standard format (AA:BB:CC:DD:EE:FF, AA-BB-CC-DD-EE-FF, or AABBCCDDEEFF) and the tool looks up the OUI (Organizationally Unique Identifier) — the first 3 bytes — in the IEEE registry to return the manufacturer name, address, and assignment type. Also generates random valid MAC addresses.

A MAC (Media Access Control) address is a 48-bit hardware identifier assigned to a network interface (NIC, Wi-Fi adapter, Ethernet port). Format: 6 pairs of hex digits (00:1A:2B:3C:4D:5E). The first 3 bytes (OUI — Organizationally Unique Identifier) identify the manufacturer, assigned by IEEE. The last 3 bytes are the NIC-specific identifier assigned by the manufacturer. The IEEE maintains the OUI registry (standards.ieee.org/products-programs/regauth).

MAC addresses are used at Layer 2 (Data Link Layer) of the OSI model for local network communication. Unlike IP addresses (routable, can change), MAC addresses are fixed to the hardware — though modern operating systems support MAC address randomization for privacy (iOS, Android, Windows, Linux all randomize MACs for Wi-Fi scanning to prevent tracking). The 7th bit (from left) of the first byte indicates if the address is locally administered (bit=1) or globally unique (bit=0).

How to Use

  1. Enter a MAC address in any format (with colons, dashes, or no separator).
  2. Click 'Lookup' to query the IEEE OUI database for the manufacturer name.
  3. See the OUI prefix, vendor name, and address associated with the manufacturer.
  4. Use 'Generate random MAC' to create a valid random MAC address for testing.
  5. Use 'Check local/global bit' to see if the address is locally administered or globally unique.

Examples

Lookup vendor

Result: 00:1A:2B:xx:xx:xx → OUI: 00:1A:2B → Vendor: Cisco Systems, Inc.

Identify Apple device

Result: F4:F1:5A:xx:xx:xx → OUI: F4:F1:5A → Apple, Inc. → likely iPhone or Mac

Random MAC for VM

Result: Generated: 52:54:00:AB:CD:EF → 52:54:00 prefix = QEMU/KVM virtual machine MACs

Frequently Asked Questions

What is an OUI and how does MAC address lookup work?

OUI (Organizationally Unique Identifier) is the first 3 bytes (24 bits) of a MAC address, assigned by the IEEE Registration Authority to hardware manufacturers. A manufacturer pays a fee to register an OUI block, then assigns unique MAC addresses from that block to their devices. The IEEE maintains a public OUI database (download as CSV). MAC lookup tools query this database to map the first 3 bytes to a vendor name. Some vendors have hundreds of OUIs (large companies like Cisco or Apple), some have just one.

Why doesn't MAC address lookup always work?

MAC lookup may fail or be inaccurate for several reasons: (1) MAC randomization — modern devices (iOS 14+, Android 10+, Windows 10+) use random MACs when scanning for Wi-Fi networks to prevent tracking. These random MACs have the locally-administered bit set (second-least-significant bit of first byte = 1). (2) Virtual machines — hypervisors (VMware, VirtualBox, QEMU) assign MACs from their own OUI blocks. (3) OUI block transfers — companies acquire or are acquired, OUIs may transfer to new owners. (4) Custom-assigned MACs in enterprise environments.

What is the difference between unicast, multicast, and broadcast MAC addresses?

The least significant bit of the first byte determines unicast vs multicast: 0 = unicast (sent to one device), 1 = multicast (sent to a group of devices). Broadcast: FF:FF:FF:FF:FF:FF is the universal broadcast address — all devices on the segment receive frames with this destination. Common multicast MACs: 01:00:5E:xx:xx:xx (IPv4 multicast), 33:33:xx:xx:xx:xx (IPv6 multicast), 01:80:C2:00:00:00 (Spanning Tree Protocol). The second bit of the first byte: 0 = globally unique (IEEE-assigned), 1 = locally administered.

How does MAC address randomization work?

To prevent device tracking across Wi-Fi networks, modern operating systems randomize the MAC address used for probe requests (scanning for networks) and for connecting to networks. iOS 14+ (2020), Android 10+ (2019), Windows 10 1903+ support MAC randomization. The randomized MAC has the locally-administered bit set (the 7th bit from the left in the first octet). Locally-administered MACs won't match any OUI in the IEEE database (they're not manufacturer-assigned). You can usually identify a randomized MAC by checking this bit. Some enterprise Wi-Fi systems (802.1X, WPA-Enterprise) require device-registered MACs and break with randomization.

What is a MAC address used for in networking?

MAC addresses operate at Layer 2 (Data Link Layer) of the OSI/TCP-IP model. Uses: Ethernet frames use destination MAC to deliver frames within the same network segment (LAN). ARP (Address Resolution Protocol) maps IP addresses to MAC addresses (or NDP for IPv6). Wi-Fi association uses MAC to identify client devices. Switches build MAC address tables to know which port each device is connected to. DHCP servers optionally assign fixed IPs based on MAC. Network access control (NAC) can restrict network access based on MAC — though this is not a strong security measure since MACs can be spoofed.

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