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How Long a USB Cable Can Be and How to Beat the Limits?
 Feb 03, 2023|View:496

USB Standards, Bandwidth and Recommended Cable Lengths:

USB Version

Bandwidth

Nominal Cable Length

USB 1.0 (Full Speed)

12Mbps

≤ 3m (9.8ft)

USB 2.0 (High Speed)

480Mbps

≤ 5m (16.4ft)

USB 3.2 Gen 1

5Gbps

≤ 3m (9.8ft)

USB 3.2 Gen 2

10Gbps

≤ 3m (9.8ft)

USB 3.2 Gen 2x2 (USB C only)

20Gbps

≤ 3m (9.8ft)

USB4 (USB C only)

40Gbps

≤ 0.8m (2.6ft)

Note: The cable lengths listed in the table are for reference only and represent the practical lengths based on cable performance requirements.

To achieve full Gen 3 40Gbps performance, USB4 cables must be shorter than 0.8m. Gen 2 or 20Gbps cables can be up to 2m. A cable longer than that can still function but may degrade performance.

For Thunderbolt 3, active Thunderbolt 3 cables support 40Gbps data transfer speed at lengths of up to 2m. Fiber optic cables are targeted later, with lengths up to 60m. Passive lower-cost cables are only capable of 20Gbps data transfer at 1m or 2m lengths but can achieve full 40Gbps at a shorter cable length of 0.5m.


How to extend the cable length?

There are several ways to extend the length of your existing cable, or even break the length limit shown above. In addition to the extension cables that we will think of, there are some rare but practical methods. It's important to note that adding another link to the connection can create a bottleneck. The entire connection will transfer data only at the speed of the slowest part of the connection.

1. USB Extension Cable

The easiest solution is to buy an extension cable, passive or active. But if the total connection exceeds the effective limit of the cable, this will result in weak signals and packet loss. Things can be trickier when using passive extension cables. However, the most significant limitation on the cable's length is the cable's quality. Results may vary, but a good quality cable with thicker gauge copper conductors and better shielding can reduce signal loss when going past the recommended lengths. Besides, to ensure you get the best results, use an active extension cable (also called a USB repeater) when exceeding the nominal limit.

2. USB Hub

Another option is a USB hub. These hubs are great for providing extra ports, and some include a fairly long main cable that provides an extra range. That's not their exact usage, but they can extend your USB cable in a pinch. The extended length should not exceed the recommended connection length, so as not to cause a communication delay between the USB host and the USB device.

3. USB over Ethernet Extenders

A USB over Cat5e/Cat6/Cat7 Ethernet extension adapter is a hub with a USB port (or multiple) and an Ethernet port. This simple USB adapter converts the USB signal into a form that can be transmitted over an Ethernet cable and then reassembled into a standard USB signal on the other end. Most USB extenders can transfer data up to 50m (164ft) without loss of signal. It can reach speeds up to 1000Mbps when using a USB 3.0+ device and cable along with a Cat5e or higher cable. This should not be confused with a USB network adapter, which allows an Ethernet connection through a USB port.

4. USB over Fiber Extenders

The USB over Fiber extension adapter is an adapter with USB ports and fiber-optic ports. Similarly, the adapter converts the USB signal to transmit through a fiber-optic cable and then converts it back to USB on the other side with another adapter. It can reach speeds of 5 to 10Gbps when using a USB 3.0+ device and cable as well as a fiber optic cable. The USB over Fiber Extender lets you mount your USB devices anywhere and is the best choice for maximum distance, such as printers, scanners, hard drives, audio devices, touchscreens, and webcams that require a long distance from a laptop or PC.