USB 3.1 have you confused? Here’s everything you need to know about the standard

The reliable Universal Serial Bus port standard is among the most commonly used on the planet. But the USB Implimenters Forum, a compendium formed between companies like Intel, Microsoft, Apple, and HP to oversee the standard’s development, isn’t resting on its laurels. The latest version of the standard is USB 3.1, and new devices and computer components that adhere to it are just starting to arrive on the market. So how is it different (and better) than older versions, like USB 2.0 and 3.0? And what’s the difference between 3.1 Gen 1 and Gen 2?

The A-B-Cs of USB ports

First of all, USB 3.1 is the standard, and shouldn’t be confused with the shape of the ports in your computer or the cables that plug into it. USB 3.1 devices and computers are able to use both of the current plugs: Type-A, the rectangular plug that’s used by the majority of devices, Type-B, the square-shaped plug that’s mostly used for printers, external hard drives. Smaller plugs like Mini USB and Micro USB may not be compatible, so sometimes the expanded USB Micro Type-B is used, as on phones like the Galaxy Note 3. This allows for the faster data transfer rate in the USB 3.0 spec, but still allows the older MicroUSB cables to be used for standard charging and data transfer.


A standard Type-A cable, used for most current PC accessories.

USB 3.0/3.1 is also compatible with USB Type-C, the latest plug design that’s just starting to gain adoption thanks to devices like the new 2015 MacBook, the second-generation Chromebook Pixel, and the OnePlus 2 smartphone. This reversible plug is distinct from USB 3.1, though manufacturers may choose to support both at once, which is certainly possible. For example, the 2015 MacBook and the second-gen Chromebook support the USB 3.1 standard on their Type-C ports, while the OnePlus 2 uses the USB 2.0 standard despite a Type-C port.

Emtec DUO USB Type-A and Type-C Drive

Flash drives that include both USB Type-A ports (larger) and Type-C ports (smaller).

As we progress into 2016 and beyond, expect more full motherboards, laptops, tablets, and smartphones to be equipped with USB Type-C ports, which are desirable thanks to their small size and reversible design. These ports may or may not be equipped with USB 3.1 or later revisions, due to expense or hardware compatibility.

Need for (data transfer) speed

The biggest improvement for the USB 3.1 standard is a boost in data transfer bandwidth of up to 10 gigabits per second. The new SuperSpeed USB specification in Generation 2 of USB 3.1 delivers improved data encoding and efficiency, doubling the speed of the Generation 1 standard (5Gbps). To put it into more practical terms, the contents a fully-loaded 50 gigabyte Blu-Ray disc could be transferred over USB 3.1 Generation 2 in just 38 seconds.

Of course, that’s assuming that you have the correct ports and cables on both ends, and that both the reading device and writing device can transfer data at that rate – the fastest consumer-grade solid state drives can only write data at a fraction of that speed. Also, Generation 2 is so new that there are very few devices currently supporting it. The slightly older standard, USB 3.1 Generation 1 only supports speeds of up to 5 gigbits per second, which is the same speed as USB 3.0. USB 3.0 and USB 3.1 Gen 1 are very similar, in fact – the latter is mostly notable thanks to the few Type-C devices that support it as well.


The new Chromebook Pixel’s USB 3.1 (Gen 1) Type-C ports can transfer data at up to 5gbps.

That being said, any USB 3.0, 3.1 Gen 1, or 3.1 Gen 2 device is preferable to the older USB 2.0 standard, which tops out at 280 megabits per second, dramatically slower than all later alternatives.

Thanks higher data throughput, USB 3.0 and 3.1 can be used to deliver video as well. There are already adapters that allow PCs and Macs to output HD video to a monitor or television via standard USB, and newer editions allow for faster and smoother video at higher resolutions. USB 3.1 supports the MHL 3 specification, which can output video at up to 4K resolution. It’s possible that USB 3.1 and USB Type-C could replace current standards and ports like HDMI, DVI, and DisplayPort, though that seems unlikely in the short term.

Related: USB 3.1 puts the pedal to the metal in early speed tests

Pump up the juice

Modern devices like phones, tablets, and even laptops are being equipped with bigger and more efficient batteries, so getting as much electricity to them as safely possible is a necessity. The latest quick-charging technologies can draw up to 15 watts and charge devices much faster than the older 2.1 standard. Even so, that’s not enough to satiate the thirst of manufacturers.

USB 3.0 and 3.1 both support the USB Power Delivery specification, which supports a maximum of 20 volts at 5 amps for a total of 100 watts of power. What that means is that there are very few portable devices that cannot be accommodated with this standard – the recently-released Macbook and Chromebook Pixel models are both charged via their USB ports with a standard power adapter, using 29 watts and 60 watts, respectively.

Comparison with Thunderbolt

Here’s where things get confusing. Intel’s proprietary Thunderbolt standard, which competes with USB 3.1, is sometimes compatible with it using the same cables. First, let’s compare speed. Thunderbolt version 3 can handle data transfer at up to 40Gbps, potentially four times as fast as USB 3.1 Gen 2. Thunderbolt versions 1 and 2 used a proprietary cable that is not compatible with USB, so some computers like the Macbook Pro included both USB and Thunderbolt 3 ports.


Older Apple laptops use the Thunderbolt 2 port (lighting icon).

Bill Roberson/Digital Trends
Bill Roberson/Digital Trends

Starting with Thunderbolt 3, Intel switched to USB Type-C ports and cables and made the standard cross-compatible with USB 3.1. That means that if the manufacturer supports it, the same device can use both Thunderbolt and USB 3.1 operating modes to transfer data, video, and power. The USB Type-C port on the 2015 Macbook is compatible with both USB 3.1 Gen 1 and Thunderbolt 3 standards, and adapters for standard USB Type-A and older Thunderbolt ports and cables are available.


The Type-C port on the new Macbook is compatible with both USB 3.1 Gen 1 and Thunderbolt 3.

Apple Inc.
Apple Inc.

At the moment Thunderbolt is mostly used on Apple devices and in specialized fields that can take advantage of its higher data throughput, such as video editing. While Apple’s MacBook and MacBook Pro line will probably continue to support it, Type-C USB ports that are compatible with both USB 3.1 and Thunderbolt 3 may be rare on PC motherboards and laptops.

RelatedThunderbolt 3 and USB Type-C might be a match made in heaven

When is it coming?

USB 3.1 Gen 1 is already available on many motherboards and a few portable devices, and the faster Gen 2 standard is appearing on portable hard drives, enclosures, and adapters. As the Type-C port gains popularity with laptop and phone manufacturers, USB 3.1 Gen 1 and Gen 2 will likely spread through the consumer electronics industry much faster. Expect flagship phones to begin supporting the Gen 2 standard later this year, with laptops and desktops to follow in 2016.

RelatedUSB 3.1 Gen 2 shows up on ASUS’ new Sabertooth mobo

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