What Is a USB Type-B Connector?

Everything you need to know about the USB Type-B connector

USB Type-B connectors, officially referred to as Standard-B connectors, are square with slight rounding or large square protrusion on the top, depending on the USB version.

Apart from USB4, every USB version supports Type-B connectors, including USB 3.0, USB 2.0, and USB 1.1. The second type of "B" connector, called Powered-B, also exists, but only in USB 3.0.

USB 3.0 Type-B connectors are often blue, while USB 2.0 Type-B and USB 1.1 Type-B connectors are often black. That's not always the case because the manufacturer can choose any color for USB Type-B connectors and cables.

A male USB Type-B connector is called a plug, while a female connector is called a receptacle or port.

USB Type-B Uses

Lifewire / Collen Tighe 

USB Type-B receptacles are often on larger computer devices like printers and scanners. Sometimes, you'll find Type-B ports on external storage devices like optical drives, floppy drives, and hard drive enclosures.

Type-B plugs are typically at one end of a USB A/B cable. The USB Type-B plug fits into the Type-B receptacle on the printer or another device, while the USB Type-A plug fits into the type A receptacle located on the host device, like a computer.


What is USB 3.0?

USB Type-B Compatibility

The Type-B connectors in USB 2.0 and USB 1.1 are identical, meaning that the USB Type-B plug from one USB version will fit into the Type-B receptacle from both its own and the other USB version.

USB 3.0 Type-B connectors are a different shape from previous ones, so the plugs do not fit in those receptacles. However, the USB 3.0 Type-B form factor was designed in such a way to allow previous USB Type-B plugs from USB 2.0 and USB 1.1 to fit with USB 3.0 Type-B receptacles.

In other words, USB 1.1 and 2.0 Type-B plugs are physically compatible with USB 3.0 Type-B receptacles, but USB 3.0 Type-B plugs are not compatible with USB 1.1 or USB 2.0 Type-B receptacles.

USB 3.0 Type-B connectors have nine pins, several more than the four pins found in previous USB Type-B connectors, to allow for a faster USB 3.0 data transfer rate. Those pins had to go somewhere, so the Type-B shape had to be altered somewhat.

There are two USB 3.0 Type-B connectors, USB 3.0 Standard-B and USB 3.0 Powered-B. The plugs and receptacles are identical in shape and follow the outlined physical compatibility rules. However, USB 3.0 Powered-B connectors have two additional pins to provide power, for a total of eleven.

See our USB Physical Compatibility Chart for a graphical representation of physical compatibility, which should help.

The mere fact that a Type-B connector from one USB version fits in the Type-B connector from another USB version doesn't imply anything about speed or functionality. 

  • Are there USB Type-B to USB Type-B cables?

    No, outside of extenders, USB Type-B is almost always paired with another USB connector, usually USB Type-A.

  • Is USB Type-B the best USB standard?

    No. Many devices use different USB connectors based on connector size and reversibility instead of speed.

  • Why isn't USB Type-B as common as other types?

    Size, mostly. The Type-B connector is large compared to, for example, USB Type-C, which you'll more often see on devices today.

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