What is USB 3.1?

USB 3.1 is becoming increasingly common on all sorts of devices, but what is it?

Razer Blade Pro 17 review ports 2
Bill Roberson/Digital Trends

Although USB connections are some of the most common for all sorts of cables and external devices, the myriad of versions and connection types can be confusing. There are a number of different generations and many types to consider, even if the more common offerings tend to fall into just one or two categories. USB 3.1 is one of the most common standards today, but what is USB 3.1? How is it different from the ones that went before and came after? That’s what we’re here to explain.

The reliable Universal Serial Bus port standard is among the most commonly used on the planet. But the USB Implementers Forum — a compendium formed between companies like Intel, Microsoft, Apple, and HP to oversee the standard’s development — is constantly working on improving it. USB 3.1 is just one of many advancements that have been made over the past two decades.

By the numbers

USB 3.1 is a generational number that mostly refers to the data transfer speed of the USB connector, not its shape or size. Officially launched in July 2013, USB 3.1 (confusingly sometimes referred to as USB 3.1 Gen 2) has a maximum transfer rate of 10 gigabits per second (Gbps). That works out to 1,250 megabytes per second (MBps) — note the capitalization. It superseded USB 3.0, which had a maximum transfer rate of 5Gbps and has since been supplanted by the still uncommon USB 3.2, which has a maximum transfer rate of 20 GBps.

All of these speeds are the theoretical maximums of the USB standard and are unlikely to be seen in everyday use, but you will certainly see an increase in transfer speed for files of most sizes when using a USB 3.1 device over one that is rated USB 3.0 only.

usb3-1a-970x0
A standard Type-A cable, used for most current PC accessories.

USB 3.1 isn’t supported by all modern devices but has slowly seen greater support over the past few years. A good example of a change between hardware generations is with Dell’s XPS 13 laptop. The 2017 XPS 13 9360 laptop shipped with two USB 3.0 ports, while the 2018 and 2019 models replaced those with USB 3.1 connections of the USB-C flavor. More on that later.

Another big advantage of USB 3.1 is that it can support a feature known as Power Delivery 2.0. It allows compatible ports to provide up to 100 watts of power to the device they’re connected to, thereby allowing for the charging of larger devices like laptops through a single USB cable. This is most commonly seen in laptops that utilize the new, USB-C standard.

USB-C isn’t the same as 3.1

macbook usb type c
Maurizio Pesce/Flickr

While often associated with USB 3.1 (and 3.2) USB-C is not the same thing. USB types, like A, B, and C, denote the shape and form-factor of the port and connector, rather than the data transfer speed. Many modern devices have moved away from the classic USB-A, USB-B, and micro-USB ports to USB-C which is small, reversible, and often goes hand in hand with faster transfer speeds. While that isn’t always the case, the fastest USB 3.2 transfer speeds are only possible on USB-C.

USB-A is still offered on a number of devices for legacy support of older accessories and cables that still use that standard, but it’s becoming increasingly common for laptops and smartphones to ship with just USB-C connectivity.

Whether a laptop, tablet, or smartphone has USB-A, USB-C, or some other connection in that wheelhouse though, it does not guarantee that it is USB 3.1. The Microsoft Surface Book 2 ships with two USB-A ports and a USB-C port, all of which are “USB Gen 1” which is actually USB 3.0, not 3.1. It’s confusing but shows how important it is to read between the lines if you care about your new hardware having the latest standards.

Thunderbolt 3

Dell XPS 13 9370 review | Ports on the left side of the laptops
Bill Roberson/Digital Trends

To make things even more confusing, USB-C ports can also be compatible with Thunderbolt 3. Thunderbolt 3 is a standard that utilizes the USB-C port and offers data transfer rates up to 40GBps — four times that of USB 3.1 and even two times that of the fastest USB 3.2. Although it can be cross-compatible with USB 3.1 cables, that’s not always the case.

Where USB 3.1 is designed more for data transfers and charging, Thunderbolt 3 targets a broader array of abilities. It is simultaneously a charging and data-transfer medium, as well as a content streaming solution. Its developer, Intel, touts its ability to charge devices, as well as send data and video to externally connected displays at the same time. By leveraging the USB-C port, its compatibility is expanded considerably over the previous generations’ mini-DisplayPort connector.

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