USB-B
USB · 4 specs
Direct Answer
USB-B (Standard-B) is the squarish connector historically used on printers, scanners, and external hard drives -- the peripheral-side counterpart to USB-A. A 9-pin SuperSpeed variant with a distinctive stacked upper tab was added for USB 3.0, though USB-C has since displaced Standard-B in most new peripheral designs.
Source: USB-IF · Last reviewed Aug 28, 2026
Specs
| Pin Count | 4 (USB 1.x/2.0) or 9 (USB 3.0+, stacked SuperSpeed tab) |
| Standard Base Dimensions | ~11.1 x 7.0 mm |
| Reversible | No |
| Typical Role | Peripheral-side port (printers, scanners, external drives) |
The Peripheral Half of the Original Pairing
USB-B was designed as the deliberately different-shaped counterpart to USB-A, so a cable's two ends couldn't be confused or plugged into the wrong kind of device -- a host always got an A connector, a peripheral always got a B connector. The USB 3.0 SuperSpeed version kept the original 4-pin B footprint intact and added a second, visually distinct tab above it carrying the 5 extra high-speed pins, so USB 2.0-only Standard-B cables still fit USB 3.0 Standard-B ports (just without the speed boost).
Standard-B has become increasingly rare on new hardware as manufacturers move peripherals to USB-C, but it remains common on printers, audio interfaces, and other equipment with long product-refresh cycles.