MAC address calculator
A MAC address is the 48-bit hardware identifier burned into every network interface, written as six pairs of hexadecimal digits such as 00:1A:2B:3C:4D:5E. This calculator parses a MAC address and breaks it into the parts that engineers actually need. It splits the address into the first three octets, the Organizationally Unique Identifier or OUI that identifies the hardware vendor, and the last three octets, the device-specific portion assigned by that vendor. It reads the two special flag bits in the very first octet: the least significant bit is the individual or group bit, which tells you whether the address is a unicast (one device) or a multicast (a group), and the next bit is the universal or local bit, which says whether the address is a globally unique factory address or a locally administered one. Finally it reports the full address as a single decimal integer. Enter your own MAC address, with colons, hyphens or no separators, to inspect a device, audit a network or check a textbook exercise. The results update as you type. Every figure here is computed deterministically from the IEEE 802 address structure, explained in full below with a worked example that reconciles exactly to the calculator.
A MAC address splits into a 24-bit OUI vendor prefix and a 24-bit device portion, with two flag bits in the first octet. For 00:1A:2B:3C:4D:5E the OUI is 00-1A-2B, the device portion is 3C-4D-5E, it is a globally unique unicast address, and the decimal value is 112,394,521,950.
MAC address structure
48 bits = 6 octets, written in hexadecimal
OUI = octets 1 to 3 (24-bit vendor prefix)
device portion = octets 4 to 6 (24 bits)
bit 0 of octet 1 = I/G bit (0 unicast, 1 multicast)
bit 1 of octet 1 = U/L bit (0 global, 1 local)
The first three octets are the vendor's Organizationally Unique Identifier and the last three are assigned by that vendor to a specific interface. The two lowest bits of the first octet carry the cast and scope flags. The whole 48-bit pattern read as one number gives the decimal value.
Worked example
Parse the MAC address 00:1A:2B:3C:4D:5E.
- OUI = first three octets = 00-1A-2B
- Device portion = last three octets = 3C-4D-5E
- First octet 00 in binary is 00000000, so the I/G bit (LSB) is 0: unicast
- The U/L bit (next bit) is 0: globally unique (factory assigned)
- Decimal = 0x001A2B3C4D5E = 112,394,521,950
The address is a globally unique unicast address with OUI 00-1A-2B and decimal value 112,394,521,950. These are the calculator's default inputs, so the results above match the widget exactly.
MAC address calculator: frequently asked questions
What is a MAC address?
A MAC (Media Access Control) address is a 48-bit identifier assigned to a network interface for communications on a local network segment. It is usually written as six hexadecimal octets and is meant to be unique to the hardware. Switches use it to deliver frames to the correct device on a LAN.
What is the OUI?
The OUI, or Organizationally Unique Identifier, is the first 24 bits (three octets) of a MAC address. The IEEE assigns each hardware manufacturer one or more OUIs, so the prefix identifies the vendor. The remaining 24 bits are chosen by that vendor to make each interface unique.
What do the unicast and local bits mean?
The least significant bit of the first octet is the individual/group bit: 0 means the address targets a single device (unicast) and 1 means a group (multicast). The next bit is the universal/local bit: 0 means a globally unique factory address and 1 means a locally administered one set by software.
Can I enter the address with hyphens or no separators?
Yes. The calculator strips colons, hyphens, dots and spaces before parsing, so 00:1A:2B:3C:4D:5E, 00-1A-2B-3C-4D-5E and 001A2B3C4D5E all work. It expects 12 hexadecimal digits in total, representing the 48-bit address.
Is the decimal value useful?
Reading the 48-bit address as a single decimal integer is handy for sorting, range checks and database storage. It is the same address, just in base ten instead of base sixteen. The conversion is deterministic and the worked example reconciles exactly to the calculator.
Official sources
- Network identifier standards and reference data: US National Institute of Standards and Technology (NIST). As at 25 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 25 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.