What Are the Types of USB Ports?

A USB port is a socket for Universal Serial Bus, the standard way to connect keyboards, storage, cameras and many other devices to a computer and to power them. The first version appeared in 1996, and the USB Implementers Forum (USB-IF) still maintains the specifications.

USB was designed around a host, normally the computer, and devices that plug into it. Early connectors were deliberately different at each end so that a cable could only go one way: a flat USB-A plug into the host and a USB-B plug into the device. Smaller devices later needed smaller plugs, which is how the family grew. USB-C reverses that thinking, with the same reversible plug at both ends.

Two things describe any USB port: its connector type, which is the physical shape, and its USB version, which sets the speed and power. A USB-A port can be a 480 Mb/s USB 2.0 port or a 10 Gb/s USB 3.2 port, and the shape alone does not tell you which.

Six connector types cover almost everything you will meet on computers and equipment today.

The table lists each connector with the fastest standard it can carry. Real ports are often slower, so check the specification of the device.

The version describes the signalling inside the port. Each one is backward compatible, so any USB device works in any port of the same connector type, running at the speed of the slower end.

• USB 1.1: 12 Mb/s, now found only on very old equipment.
• USB 2.0: 480 Mb/s. Still standard for keyboards, mice, scanners and licence dongles.
• USB 3.2 Gen 1: 5 Gb/s, first sold as USB 3.0. USB-IF now labels it USB 5Gbps.
• USB 3.2 Gen 2: 10 Gb/s, labelled USB 10Gbps.
• USB 3.2 Gen 2×2: 20 Gb/s, on USB-C only.
• USB4: 20 or 40 Gb/s, and 80 Gb/s on USB4 Version 2.0, on USB-C only.

Our explainer on how USB4 reaches 40 and 80 Gb/s covers the newest generation and its links with Thunderbolt.

The USB standards have been renamed several times, which is why the same port can appear as USB 3.0, USB 3.1 Gen 1 and USB 3.2 Gen 1. The chart lists each generation by its current USB-IF name, with the older names alongside, the year the specification was published, its top data rate and the connectors that can carry it.

Two points help when reading a datasheet. First, the speed belongs to the port and the cable, not the connector shape, so a USB-C port may still be USB 2.0. Second, power has grown separately: USB 2.0 ports supply 500 mA at 5 V and USB 3.x ports 900 mA, while USB-C with USB Power Delivery can negotiate up to 240 W. Industrial computers usually mix generations, with USB 2.0 for keyboards and dongles and 5 or 10 Gb/s ports for cameras and storage.

Because one shape can hide several speeds, look for the markings next to the port. A trident logo with SS means SuperSpeed at 5 Gb/s or more, and SS 10 or a 10 next to it means 10 Gb/s. A lightning bolt beside a USB-C port usually means Thunderbolt, and a battery symbol marks a port that charges devices even when the computer is off.

Colour helps on USB-A: a blue insert usually means USB 3, and some makers use teal for 10 Gb/s and yellow or red for always-on charging ports. The colours are a convention rather than a rule, so treat them as a hint. On USB-C, the port can carry very different features, which our guide to what a USB-C port can carry explains.

Industrial computers use USB differently from laptops. Most of our embedded box PCs keep several USB-A ports, because machine vision cameras, barcode scanners, touch screens and licence dongles still use them, and add USB-C on newer models. Ports are often split between USB 2.0 for low-speed devices and USB 3.2 for cameras and storage.

Factory and vehicle installations add mechanical needs: screw-locking or latching USB cables, internal USB headers so a dongle cannot be removed, and ports set back behind a cover. USB-C is also replacing separate video and power leads on USB-C monitors, where one cable carries the picture, touch data and power. Our white paper on industrial USB applications covers the history and the uses in more depth.

We fit the USB ports, headers and expansion cards each system needs as standard, and test every port with the connected devices before the system ships.