How it connects
Plug is pushed straight into the rectangular socket until its flexible plastic latch tab snaps into the jack's latch recess; eight spring-wire contacts in the jack press on the plug's blade contacts. Released by pressing the latch tab.
Male and female halves
Female half is the jack (socket); male half is the plug with the latch tab on the cable end. This connection is the female jack.
Usually connects to
- Unkeyed RJ45/8P8C male plug on Cat5e/Cat6/Cat6A twisted-pair Ethernet patch cable
- RJ11/RJ12 6P plug (can fit physically, but only some contacts are used and this is not the intended connection)
Common sizes
- One 8-position format: opening estimated at roughly 11.7 mm wide × 6.5–8 mm high, plus latch notch; not a manufacturing specification.
- Cat5e/Cat6/Cat6A, shielding and mounting vary without changing the mating format.
- Keystone faces are about 14.5 × 16 mm; device bodies, PCB footprints, wall plates, patch panels and floor-box mounts vary.
Where it is used
computer networking / Ethernettelecommunicationsstructured cablingPower over Ethernet devices; PoE devicesserial console portswall plates and floor boxespatch panelsVoIP telephony
Variations
- Through-hole or SMT PCB mount, vertical/right-angle
- Shielded metal-shell STP or unshielded UTP
- Integrated LEDs and/or magnetics/MagJack
- Keystone snap-in
- Female-female inline coupler
- 1-to-2 splitter
- Cat5e/Cat6/Cat6A rating, same mating face
- Punch-down or toolless rear termination
How to recognise it
Rectangular socket about 12 mm wide with a latch recess/notch on one long side and eight fine gold spring contacts visible along the opposite inside wall; often labelled LAN, ETH or with a network icon, sometimes with green/yellow LEDs at the corners.
Often confused with
| Confused with | How to tell them apart |
|---|---|
| RJ11 / RJ12 (6P2C/6P4C/6P6C) telephone jack | Telephone jack opening is narrower (about 9.6 mm) with 2-6 contacts; RJ45 is about 11.7 mm wide with 8 contacts. |
| RJ48 / 10P10C or keyed 8P8C (RJ45S) | RJ45S/keyed jacks have an extra key notch on the side; 10P10C has 10 contacts and is wider. |
| RJ11/RJ12 (6P4C/6P6C) phone jack | Narrower mouth (~9.6 mm) with 4 or 6 contacts; 8P8C has 8 contacts and a wider mouth. |
| RJ45S / 8P keyed jack | Keyed variant has an extra notch on one side of the mouth; standard Ethernet jack is unkeyed. |
| Cat6/Cat6A jack | Identical mating face; distinguished only by marking/rating, not geometry. |
Also called
Ethernet portLAN portnetwork jackkeystone jack (snap-in panel variant)Ethernet jackRJ45 keystone jackmodular data jack; 8P8C female modular connectorkeystone jack (when in keystone housing)
Good to know
Strictly, 'RJ45' is a telephone registered-jack designation and the Ethernet connector is properly 8P8C, but the industry uses both names interchangeably. Sample part is an F-F in-line coupler: both ports are this female jack.
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