USB cables explained

Connecting accessories to your laptop, charging your phone and various other devices is usually done with a USB cable.

But with various different types now available, how can you tell which is which – especially when you need to order a replacement online.

Here’s a quick guide to all the USB standards and which ones we recommend you buy. We also have the very latest on USB speeds, following announcements of USB 3.2, USB4 and Thunderbolt 4.

What are the different types of USB?

Here are all the common standards, but bear in mind that most USB cables will have different connector styles at each end, so always check before making a purchase to ensure you get the one you need.

USB-A

Up until recently this was the most common type of USB port you’d find on laptops, PCs and chargers. Easily recognisable by to its rectangular shape, when you look inside, you’ll see half is blocked by another plastic rectangle, with the section above it empty.

This is because the port that you plug a USB-A cable into will have a corresponding plastic rectangle that ensures good contact with the four connectors so that data can move between the cable and device.

This is also the reason why you have to try at least three times to plug it in, the first to discovering that it’s the wrong way up, the second to turn it over and find that it still doesn’t fit, then return to the first orientation and inexplicably the cable now slots into place. It’s why we now have USB-C which can be attached either way up.

USB-A connectors still remain ubiquitous in tech, with most laptops and PCs having at least a couple of these ports, plus the majority of USB chargers in your house will no doubt be the USB-A connector variety on the charger itself even if the port on your phone or tablet is microUSB, USB-C or Lightning.

They are also a regular fixture on power banks.

USB-A ports can operate at three speeds – 1.x, 2.0 and 3.x – although these days you’ll probably only encounter 2.0 and 3.x ports. The latter is usually identified by the plastic block on the inside being blue. They are all compatible with each other, but carry data at very different speeds, with 3.x being the fastest.

You don’t need to worry about this when buying a cable, though.

Micro-USB

Up until recently, this would have been the port and cable you’d have used to connect to your Android phone. It looks like a squashed version of Mini-USB, with a long bottom edge, angled sides and a shorter top edge.

It was also the port of choice on most digital cameras and still is on some dash cams,tablets and phone accessories. The most common cable used with Micro-USB would have a USB-A connector at the other end so that it would plug that part into a wall-charger, then the smaller connector into the phone itself.

• Here’s our pick of the best Micro-USB charging cables to buy

Micro USB-B

Another relative rarity these days is the Micro USB-B connector. This was a mainstay for external hard-drives for a while, but has mostly been superseded by USB-C. In terms of looks, it’s essentially a Micro-USB with an extra little box on the right.  

USB-C

The new kid on the block is USB-C, even though it’s been around for a few years now. These are slowly replacing the Micro-USB and USB-A types mentioned above, mainly due to the fact that USB-C is capable of far greater speeds and can handle data and power demands at the same time (also video if attached to certain devices).

This allows PCs and Macs to use various accessories via docks that you can plug into the ports, such as those found in our roundup of the best USB-C hubs and adapters.

As USB-C can also be used as the charging point for a device, it saves space as there’s no need for an additional power socket. This can lead to confusion though, as some laptops require a higher amount of power being delivered to actually charge properly. To make sure you don’t run into these issues, we recommend taking a look at our pick of the best USB-C power delivery chargers.

USB-C is easy to spot, as it has a curved rectangle design that will work the same on either side, finally putting an end to the frustrations of Micro-USB and USB-A.

There are some hidden differences though, with USB-C having already gone through two generations, USB 3.1 (Gen1) and USB 3.2 (Gen2) with the first supporting 5Gbps speeds and the second 10Gbps. The names are a bit confusing, as they all look identical and all use the USB-C shape. These waters are further muddied by Intel’s Thunderbolt 3 connector (as found on Apple’s Macs and iPad Pros) which is faster still at 40Gbps.

Again, they generally all work in harmony, but if you’re curious of the differences, then it would be worth reading What is USB-C?

USB-C is now the standard charging port on Android phones, many laptops (it’s all you get on Apple Macs), plus tablets and most new tech.

• See our best USB-C charging cables guide for recommendations.

What USB cable do I need for my iPhone?

Apple has stubbornly resisted the new USB-C standard on the iPhone, though it is now present on some iPads. But you’re need the proprietary Lightning cable to charge your iPhone still. If you want to know the difference, read our Lightning vs USB-C comparison.

USB-B

This one isn’t around as much as in the past, but you’ll still find it in use with printers, external CD drives, some audio interfaces (and microphones) and other peripherals. The connector is a little like a 2D rendition of a house, as it is a square with the two angled sides leaning in to join the ‘roof’.

Mini-USB

Again, this style has pretty much dropped out of use, but it still crops up on older DSLR cameras, dash cams, some USB microphones and the odd other accessory. Essentially, it looks a bit like cutting a USB-B connector in half and only keeping the top section that contains the angled edge and ‘roof’, albeit with a little more of a curvy edge.

Typically the other end will the USB-A for connection to a PC or laptop.