Which company owns MAC address prefix 40:4A:D4?

MAC address prefix 40:4A:D4 is registered to Widex A/S in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 40:4A:D4 has a network interface built by Widex A/S.

What is the OUI 40:4A:D4?

40:4A:D4 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Widex A/S. It covers every address from 40:4A:D4:00:00:00 to 40:4A:D4:FF:FF:FF, or 16,777,216 addresses in total. It is also written 40-4A-D4.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 40:4A:D4:00:00:00 that is 40:4A:D4 — and look that prefix up in the IEEE OUI registry. If the second-lowest bit of the first octet is set, the address is locally administered (a randomized or private MAC), which belongs to no manufacturer and will not resolve; modern phones and laptops use these by default on each network.

Where is Widex A/S located?

Widex A/S is listed at Nymoellevej 6 Lynge Alleroed DK DK3540 in the IEEE OUI registry entry for 40:4A:D4. This is the address the organization registered with the IEEE, which may differ from its current operating address.

How many MAC prefixes does Widex A/S own?

Widex A/S holds 2 OUI prefixes in the IEEE registry, of which 40:4A:D4 is one. A device made by Widex A/S could carry a MAC address from any of them.

Widex A/S

MAC address prefix 40:4A:D4 is registered to Widex A/S in the IEEE OUI registry. Any device whose MAC address begins with 40:4A:D4 has a network interface built by Widex A/S. This prefix (the OUI, or Organizationally Unique Identifier) is assigned by the IEEE and is the first three octets of the address — it covers every MAC from 40:4A:D4:00:00:00 to 40:4A:D4:FF:FF:FF.

OUI prefix: 40:4A:D4
Hyphen form: 40-4A-D4
MAC range: 40:4A:D4:00:00:00 – 40:4A:D4:FF:FF:FF
Addresses in block: 16,777,216
Organization: Widex A/S
Address: Nymoellevej 6 Lynge Alleroed DK DK3540
Source: IEEE OUI registry

Have a full MAC address? Look it up— we'll also tell you if it's a randomized (private) address rather than a real manufacturer prefix.

Other prefixes from Widex A/S

Widex A/S holds 2 OUI prefixes in total. A device with this exact prefix could just as well carry any of these:

84:D4:C8

Assignment history (2)

The IEEE registry publishes current state only — this is the change record we've kept since we started tracking it daily.

2016-07-29Assigned to "Widex A/S"
archived source →
2026-07-17Assigned to "Widex A/S"

Nearby in the registry

The prefixes assigned immediately before and after 40:4A:D4:

FAQ

Which company owns MAC address prefix 40:4A:D4?: MAC address prefix 40:4A:D4 is registered to Widex A/S in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 40:4A:D4 has a network interface built by Widex A/S.
What is the OUI 40:4A:D4?: 40:4A:D4 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Widex A/S. It covers every address from 40:4A:D4:00:00:00 to 40:4A:D4:FF:FF:FF, or 16,777,216 addresses in total. It is also written 40-4A-D4.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 40:4A:D4:00:00:00 that is 40:4A:D4 — and look that prefix up in the IEEE OUI registry. If the second-lowest bit of the first octet is set, the address is locally administered (a randomized or private MAC), which belongs to no manufacturer and will not resolve; modern phones and laptops use these by default on each network.
Where is Widex A/S located?: Widex A/S is listed at Nymoellevej 6 Lynge Alleroed DK DK3540 in the IEEE OUI registry entry for 40:4A:D4. This is the address the organization registered with the IEEE, which may differ from its current operating address.
How many MAC prefixes does Widex A/S own?: Widex A/S holds 2 OUI prefixes in the IEEE registry, of which 40:4A:D4 is one. A device made by Widex A/S could carry a MAC address from any of them.