MAC Address Validator - Validate & Decode MAC Addresses

How to use this tool

1. Enter one MAC address or switch to Bulk and paste a list, one address per line or comma-separated.
2. Review the normalized forms, address type, local OUI match, and derived IPv6 values.
3. Copy an individual notation or export all or valid bulk results as CSV.

MAC Address Validator

A MAC (Media Access Control) address is a 48-bit identifier assigned to a network interface. This browser-based tool checks its structure, normalizes the value, identifies address-type bits, and checks the first three octets against a small local OUI vendor subset. No address you enter is sent to a server.

Accepted formats

• Colon: AA:BB:CC:DD:EE:FF (common on Linux and macOS)
• Hyphen: AA-BB-CC-DD-EE-FF (common on Windows)
• Cisco dot: AABB.CCDD.EEFF
• Raw hex: AABBCCDDEEFF
• Space-separated or mixed colon/hyphen: six two-digit hexadecimal octets

Spaces between octets and mixed colon/hyphen separators are accepted only when all six groups contain exactly two hexadecimal digits. The parser does not strip arbitrary punctuation or surrounding text, so a paste cannot become valid just because it contains twelve hexadecimal characters.

Address types

Broadcast (FF:FF:FF:FF:FF:FF) is delivered to all devices on a network segment. Multicast addresses have the least-significant bit of the first octet set to 1. Locally administered addresses (LAA) have the next bit set. Operating systems use this bit for Wi-Fi privacy addresses, and virtual networks can assign local addresses too. The result labels distinguish unicast from multicast and universal from locally administered addresses.

OUI examples

The first three octets (24 bits) form the OUI, or Organizationally Unique Identifier, a prefix assigned by the IEEE. These examples are also the complete vendor subset bundled in this tool:

A match means the prefix appears in this tool’s local list; it does not confirm a device’s current owner or prove that the device is genuine. “Not in local subset” does not mean “unregistered.” For other assignments, consult the IEEE Registration Authority .

IPv6 from a MAC address

A modified EUI-64 interface identifier is made by inserting FF:FE between the third and fourth MAC octets and flipping the universal/local bit in the first octet. The tool shows that value and combines it with the fe80:: link-local prefix. This conversion is useful when learning IPv6 addressing or checking older router and embedded-device configurations. It is a reference value, not proof that a host uses it: modern systems often use privacy extensions instead of exposing a hardware-derived address.

Validate a list

Switch to Bulk to check one address per line or comma-separated addresses. Valid and invalid entries are reported independently, so a typo in one row does not hide the rest of the list. The browser processes up to 500 entries at a time and can copy all rows or only valid rows as CSV for a DHCP reservation worksheet or router access-control list.

Privacy and MAC randomization

Modern operating systems randomize MAC addresses when scanning for Wi-Fi networks to prevent tracking. iOS 14+, Android 10+, and Windows 10/11 all enable MAC randomization by default for Wi-Fi probe requests. When connected to a saved network, a randomized (but stable) address is typically used per network.

A randomized address has the U/L bit (the second bit in the first octet) set. A virtual network or manual configuration can set it too, so the flag alone cannot identify why the address is local.

Common use cases

• Router MAC filtering: validate the address format before adding a device to an allow-list, which can prevent typo-related lockouts.
• DHCP reservations: review the MAC before assigning a fixed IP to a server, printer, or smart-home device.
• Network inventory: a recognized OUI can suggest an interface vendor while reviewing a DHCP or switch inventory. OUI matches are clues, not device authentication; MAC addresses can be randomized or spoofed.