Which company owns MAC address prefix 5C:75:AF?

MAC address prefix 5C:75:AF is registered to Fitbit, Inc. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 5C:75:AF has a network interface built by Fitbit, Inc..

What is the OUI 5C:75:AF?

5C:75:AF is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Fitbit, Inc.. It covers every address from 5C:75:AF:00:00:00 to 5C:75:AF:FF:FF:FF, or 16,777,216 addresses in total. It is also written 5C-75-AF.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 5C:75:AF:00:00:00 that is 5C:75:AF — 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 Fitbit, Inc. located?

Fitbit, Inc. is listed at 199 Fremont Street, 14th Fl San Francisco CA US 94105 in the IEEE OUI registry entry for 5C:75:AF. This is the address the organization registered with the IEEE, which may differ from its current operating address.

How many MAC prefixes does Fitbit, Inc. own?

Fitbit, Inc. holds 4 OUI prefixes in the IEEE registry, of which 5C:75:AF is one. A device made by Fitbit, Inc. could carry a MAC address from any of them.

Fitbit, Inc.

MAC address prefix 5C:75:AF is registered to Fitbit, Inc. in the IEEE OUI registry. Any device whose MAC address begins with 5C:75:AF has a network interface built by Fitbit, Inc.. 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 5C:75:AF:00:00:00 to 5C:75:AF:FF:FF:FF.

OUI prefix: 5C:75:AF
Hyphen form: 5C-75-AF
MAC range: 5C:75:AF:00:00:00 – 5C:75:AF:FF:FF:FF
Addresses in block: 16,777,216
Organization: Fitbit, Inc.
Address: 199 Fremont Street, 14th Fl San Francisco CA US 94105
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 Fitbit, Inc.

Fitbit, Inc. holds 4 OUI prefixes in total. A device with this exact prefix could just as well carry any of these:

Assignment history (2)

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

2019-07-04Assigned to "Fitbit, Inc."
archived source →
2026-07-17Assigned to "Fitbit, Inc."

Nearby in the registry

The prefixes assigned immediately before and after 5C:75:AF:

FAQ

Which company owns MAC address prefix 5C:75:AF?: MAC address prefix 5C:75:AF is registered to Fitbit, Inc. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 5C:75:AF has a network interface built by Fitbit, Inc..
What is the OUI 5C:75:AF?: 5C:75:AF is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Fitbit, Inc.. It covers every address from 5C:75:AF:00:00:00 to 5C:75:AF:FF:FF:FF, or 16,777,216 addresses in total. It is also written 5C-75-AF.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 5C:75:AF:00:00:00 that is 5C:75:AF — 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 Fitbit, Inc. located?: Fitbit, Inc. is listed at 199 Fremont Street, 14th Fl San Francisco CA US 94105 in the IEEE OUI registry entry for 5C:75:AF. This is the address the organization registered with the IEEE, which may differ from its current operating address.
How many MAC prefixes does Fitbit, Inc. own?: Fitbit, Inc. holds 4 OUI prefixes in the IEEE registry, of which 5C:75:AF is one. A device made by Fitbit, Inc. could carry a MAC address from any of them.