Differences between RJ11 and RJ45
RJ11 vs. RJ45[edit]
RJ11 and RJ45 are two common types of registered jack (RJ) connectors used in telecommunications and data networking.[1][2] While they appear similar, they have distinct differences in size, pin configuration, and application.[1][3] RJ11 connectors are primarily used for telephone lines, while RJ45 connectors are the standard for Ethernet networking.[4][5]
The most noticeable physical difference between the two is their size.[3] RJ45 connectors are wider to accommodate more internal wires.[2] An RJ45 connector is an 8P8C (eight position, eight contact) connector, meaning it has eight pins and eight contacts. In contrast, the RJ11 connector is smaller and typically uses a 6P4C (six position, four contact) or 6P2C (six position, two contact) configuration. This means that while the RJ11 connector has six available positions for pins, only two or four of them are actively used for wiring.
Their primary functions are also different. RJ11 connectors are the standard for connecting analog telephones, fax machines, and modems to a telephone line. They are designed to carry voice signals over a pair of twisted copper wires. RJ45 connectors, on the other hand, are used for high-speed data transmission in local area networks (LANs). They are paired with Ethernet cables, such as Cat5 and Cat6, to connect computers, routers, and other network devices.[4][5]
Due to its larger size and more numerous pin connections, the RJ45 is capable of supporting significantly higher bandwidth than the RJ11. An RJ45 connector can support speeds up to 10 Gbps over Ethernet, whereas an RJ11 is generally limited to much lower data rates, such as those used for DSL (Digital Subscriber Line) services.[5] While an RJ11 plug can physically fit into an RJ45 jack, it is not recommended as it can cause a poor connection or even damage the RJ45 port's pins over time. An RJ45 plug is too wide to fit into an RJ11 jack.[5]
Comparison Table[edit]
| Category | RJ11 | RJ45 |
|---|---|---|
| Primary Use | Telephone, ADSL, Fax Machines | Ethernet Networking[1][5] |
| Size | Smaller, more compact[1] | Larger, wider[3][2] |
| Pin Configuration | 6P4C or 6P2C (6 position, 4 or 2 contact) | 8P8C (8 position, 8 contact) |
| Number of Wires | Typically 4 wires[2] | 8 wires[2] |
| Bandwidth | Up to 24 Mbps[5] | Up to 10 Gbps |
| Cable Type | Telephone Cable | Ethernet Cable (Cat5, Cat6, etc.)[4] |
| Interchangeability | Plug fits in RJ45 jack (not recommended) | Plug does not fit in RJ11 jack[5] |
References[edit]
- ↑ 1.0 1.1 1.2 1.3 "thenetworkinstallers.com". Retrieved December 23, 2025.
- ↑ 2.0 2.1 2.2 2.3 2.4 "router-switch.com". Retrieved December 23, 2025.
- ↑ 3.0 3.1 3.2 "cbtnuggets.com". Retrieved December 23, 2025.
- ↑ 4.0 4.1 4.2 "cablematters.com". Retrieved December 23, 2025.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 "nassaunationalcable.com". Retrieved December 23, 2025.
