USB Type B

Everything you need to know about the USB Type B connector

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Photo of Tim Fisher, Lifewire GM and Writer
Tim Fisher
VP and General Manager, Lifewire.com

Tim Fisher has more than 30 years' of professional technology experience. He's been writing about tech for more than two decades and serves as the VP and General Manager of Lifewire.

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Tim Fisher
Updated on June 12, 2021

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

USB Type-B connectors are supported in every USB version, 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 the color blue while USB 2.0 Type B and USB 1.1 Type B connectors are often black. This is not always the case because USB Type B connectors and cables can come in any color the manufacturer chooses.

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

USB Type B Uses

Illustration of a USB Type B connector snaking through various devices
Lifewire / Collen Tighe 

USB Type B receptacles are most commonly seen on larger computer devices like printers and scanners. You'll also sometimes find USB Type B ports on external storage devices like optical drives, floppy drives, and hard drive enclosures.

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

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What is USB 3.0?

USB Type B Compatibility

The USB 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 USB Type B receptacle from both its own and the other USB version.

USB 3.0 Type B connectors are a different shape than previous ones and so the plugs do not fit in previous receptacles. However, the new 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.

The reason for the change is that 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 the 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 actually 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 physical compatibility rules already outlined, but USB 3.0 Powered-B connectors have two additional pins to provide power, for a total of eleven pins.

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. 

FAQ
  • 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 different devices use different USB connectors based on connector size and reversibility, as opposed to 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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