What Is a MAC Address Lookup?
A MAC address lookup is the process of identifying the manufacturer or vendor of a network device by examining its MAC (Media Access Control) address. Every network interface card (NIC) — whether in a laptop, smartphone, router, or IoT device — is assigned a unique 48-bit MAC address at the factory. The first three bytes of this address form the OUI (Organizationally Unique Identifier), which reveals who manufactured the hardware.
The IEEE (Institute of Electrical and Electronics Engineers) maintains the official registry of OUI assignments. When a hardware manufacturer wants to produce network devices, they register with the IEEE and receive one or more unique OUI prefixes. This system ensures that every legitimately manufactured network device has a globally unique MAC address that can be traced back to its vendor.
Our free MAC address vendor lookup tool queries this OUI database to instantly identify the manufacturer behind any MAC address. Whether you're performing network inventory, investigating unknown devices on your network, or verifying hardware authenticity, a MAC address lookup provides the starting point for device identification. You can also use our IP Lookup tool to identify devices by IP address, or DNS Lookup to resolve domain names associated with network devices.
How MAC Address Lookup Works
Our MAC address lookup tool follows a simple four-step process to identify the vendor behind any MAC address. The entire lookup completes in milliseconds, providing instant results from the IEEE OUI database.
Enter MAC Address
Input the MAC address in any format — colon-separated, dash-separated, dot notation (Cisco), or plain hex. The tool automatically normalizes all formats.
Extract OUI (First 3 Bytes)
The first 24 bits (3 bytes) of the MAC address are extracted as the OUI prefix. For example, from AA:BB:CC:DD:EE:FF, the OUI is AA:BB:CC.
Query IEEE OUI Database
The OUI prefix is looked up against the IEEE registration authority database containing over 30,000 registered vendor assignments worldwide.
Vendor Information Returned
The matched vendor/manufacturer name is displayed along with format conversions, unicast/multicast flag, and universal/local administration bit status.
Understanding Your MAC Address Lookup Results
When you perform a MAC address vendor lookup, the results include several key pieces of information about the network hardware. Here's what each field means:
Vendor / Manufacturer Name
The organization registered with the IEEE as the OUI owner. This identifies who manufactured the network interface — e.g., Apple, Samsung, Intel, Cisco, TP-Link.
OUI Prefix
The first 3 bytes (6 hex characters) of the MAC address that identify the vendor. A single manufacturer may own multiple OUI prefixes due to high device production volume.
Unicast / Multicast Flag
The least significant bit of the first byte. Unicast (0) means the address targets a single device. Multicast (1) means it targets a group of devices on the network.
Universal / Local Admin Flag
The second bit of the first byte. Universally administered (0) means the address was assigned by the manufacturer. Locally administered (1) means it was set by software (randomized or spoofed).
What Does "Unknown Vendor" Mean?
If the lookup returns "Unknown Vendor," the OUI prefix wasn't found in the IEEE registry. This commonly happens with MAC address randomization — a privacy feature enabled by default on iOS 14+, Android 10+, and Windows 10/11. Randomized addresses use locally administered bits, meaning they aren't tied to any vendor. It can also occur with private OUI assignments or very recently registered prefixes.
MAC Address Formats Explained
MAC addresses can be written in four different formats depending on the operating system or network equipment. Our MAC address lookup tool accepts all formats and automatically converts between them.
| Format | Example | Used By |
|---|---|---|
| Colon-separated | AA:BB:CC:DD:EE:FF | Linux, macOS |
| Dash-separated | AA-BB-CC-DD-EE-FF | Windows |
| Dot-separated | AABB.CCDD.EEFF | Cisco IOS |
| Plain (no separator) | AABBCCDDEEFF | Programming, APIs |
All four formats represent the same 48-bit address. Our tool normalizes the input by stripping all separators before performing the OUI lookup, so you can paste any format directly from your terminal or network management tool.
Common Uses for MAC Address Lookup
MAC address lookups are essential for network administrators, security professionals, and IT teams. Here are the most common use cases for identifying device vendors by MAC address:
Network Device Identification
Identify unknown devices on your network by matching their MAC addresses to manufacturers. Useful for distinguishing laptops from IoT devices, printers, and network equipment.
Security Auditing
Detect unauthorized devices by checking if their vendor matches expected hardware. A MAC from an unexpected manufacturer may indicate a rogue device or intrusion attempt.
Network Inventory
Build comprehensive asset inventories by categorizing devices by manufacturer. Track hardware across your organization for lifecycle management and procurement planning.
Troubleshooting
Diagnose network issues by identifying device types. Knowing the manufacturer helps determine firmware versions, known bugs, and vendor-specific configuration requirements.
Vendor Verification
Verify that hardware is genuine by confirming its OUI matches the claimed manufacturer. Counterfeit network equipment often uses incorrect or unregistered OUI prefixes.
Access Control Lists
Configure MAC-based access control on network switches and wireless access points. Understanding vendor prefixes helps define allow/deny rules for device categories.
MAC Address Structure Explained
A MAC address is a 48-bit (6-byte) identifier structured into two halves. Understanding this structure helps you interpret OUI lookup results and identify special-purpose addresses.
OUI — Bytes 1-3 (Vendor ID)
The first 3 bytes are the Organizationally Unique Identifier assigned by the IEEE. This portion identifies the manufacturer. The IEEE charges approximately $3,000 per OUI registration, and over 30,000 OUIs are currently assigned.
NIC-Specific — Bytes 4-6 (Device ID)
The last 3 bytes are assigned by the manufacturer to uniquely identify each device. With 24 bits, each OUI allows up to 16.7 million unique device addresses. Manufacturers with high production volumes (Apple, Samsung) hold multiple OUI registrations.
48-Bit MAC Address Structure
How to Find Your MAC Address
Before you can look up the vendor of a MAC address, you need to find it on your device. Here are the commands and steps for each major platform:
Windows
Open Command Prompt and run:
ipconfig /allLook for "Physical Address" under your network adapter. Alternatively, run getmac for a quick list of all MAC addresses.
macOS
Open Terminal and run:
ifconfig en0 | grep etherOr go to System Settings > Network > Advanced > Hardware. Use en0 for Wi-Fi, en1 for Ethernet.
Linux
Open a terminal and run:
ip link showLook for the link/ether line under your interface. The legacy command ifconfig also works on most distributions.
Mobile (iOS / Android)
Navigate to device settings:
Note: Modern mobile devices show a randomized MAC by default. The real hardware address may differ from the per-network randomized address.
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Frequently Asked Questions
What is a MAC address lookup?
A MAC address lookup identifies the manufacturer or vendor of a network device by examining the first three bytes (OUI) of its 48-bit MAC address. The IEEE assigns unique OUI prefixes to hardware manufacturers, making it possible to determine who made a network adapter, router, or IoT device from its MAC address.
What is an OUI in MAC addresses?
OUI stands for Organizationally Unique Identifier. It's the first 3 bytes (24 bits) of a MAC address, assigned by the IEEE to hardware manufacturers. For example, the OUI 00:1A:11 is assigned to Google. Over 30,000 OUI assignments exist in the IEEE registry.
How do I find the vendor of a MAC address?
Enter any MAC address into the lookup tool above in any format — colon, dash, dot, or plain hex. The tool extracts the OUI prefix and queries the IEEE database to identify the vendor. Results are instant and free.
Why does my MAC address show "Unknown Vendor"?
This typically means the device uses MAC address randomization (iOS 14+, Android 10+, Windows 10/11), has a private OUI assignment, or the prefix was very recently registered. Locally administered addresses (second bit of first byte = 1) aren't tied to any vendor.
What MAC address formats does this tool support?
All four common formats: colon-separated (AA:BB:CC:DD:EE:FF for Linux/macOS), dash-separated (AA-BB-CC-DD-EE-FF for Windows), dot-separated (AABB.CCDD.EEFF for Cisco IOS), and plain hex (AABBCCDDEEFF for programming). All are automatically normalized.
Is a MAC address the same as an IP address?
No. A MAC address is a 48-bit hardware identifier assigned at the factory (Layer 2), while an IP address is a logical network address (Layer 3). MAC addresses identify devices on a local network; IP addresses route traffic across the internet. Use our IP Lookup tool for IP-based identification.
Can MAC addresses be spoofed or changed?
Yes. MAC addresses can be changed in software on all major operating systems, even though the hardware address remains the same. This is used for privacy, testing, and bypassing MAC-based access controls. Spoofed addresses are indistinguishable from real ones on the network.
What is MAC address randomization?
A privacy feature in iOS 14+, Android 10+, and Windows 10/11 that generates random, locally administered MAC addresses instead of using the real hardware address. This prevents tracking across Wi-Fi networks. Randomized MACs have the locally administered bit set (bit 1 of byte 1 = 1).
How many MAC address vendors are registered?
The IEEE OUI registry contains over 30,000 registered vendor assignments. Major vendors like Apple, Samsung, Intel, and Cisco hold dozens of OUI prefixes each. The IEEE also offers MA-M (Medium) and MA-S (Small) blocks for organizations needing fewer addresses.
Is this MAC address lookup tool free?
Yes, completely free with no registration required. Look up any MAC address to identify its vendor, view all format conversions, check unicast/multicast and universal/local flags, and copy results with one click. Unlimited lookups for all users.