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18 March 2021

USB, HDMI and more: the ultimate guide to computer ports

Puzzled about the ports on your current computer or trying to understand what the USB-C ports on your next laptop are capable of? We explain the differences between USB, HDMI, Ethernet and more.
Plugging into a laptop
Michael Passingham

Ports and connectors might not be the most exciting part of buying a computer, but knowing what you have and how they work will make a huge difference in how easy your computer is to use throughout its life.

Choosing a laptop with the right ports for your needs could save you money down the line, as you won’t have to invest in extra adaptors and docks to get your computer working exactly how you want it. 

All our laptop reviews have details on what ports and adapters are present on each laptop, and our overall Which? test scores take into account how easy those ports are to use and how fast a laptop’s USB speeds are.

Find out which laptops have the range of ports you’ll need in our full laptop reviews.

What are the different types of computer port?

The most common ports you’ll come across on modern computers are USB, HDMI and Ethernet ports, and SD card readers. 

To complicate matters, there are different types of each port, which operate in slightly different ways. USB, for example, breaks down into USB-A, USB-B, and USB-C.

Some computers only have one type of port, while others have half a dozen, so it’s worth spending some time thinking about what you actually need.

The image below shows the ports you'll typically find on most laptops, but not every laptop will have all of these ports. 

These are the most common ports on modern laptops

What is a USB port used for?

Whether you’re trying to connect a printer, charge a phone or plug in a mouse, a USB port can do it all. These ports are very much jacks of all trades –in fact, the ‘U’ in USB stands for ‘universal’.

You might ask, then, why some laptops have ports of different shapes and sizes that all claim to be USB. 

Are all USB ports the same?

In short, no. There are two aspects of a USB port that matter:

  • Their physical shape and size, which dictates what connectors fit what ports.
  • The USB connection speed. 

Different ports combine these elements in different ways for reasons of cost and convenience. Below, we’ll first explain the different shapes and sizes you’ll come across, and then the different data speeds.

Different USB shapes and sizes: USB-A, USB-B and USB-C

USB-A

This is the USB port that most people will be familiar with – its asymmetrical design means that connectors can only be plugged in one way up. 

You’ll find USB-A ports on  all desktop computers and most laptops, but not on many non-computing devices, aside from phone chargers that you plug into the wall. 

Most USB cables have a USB-A connector to slot into your computer on one end, and then either some form of USB-B or USB-C that you attach to a smartphone or other device on the other.

Plus, of course, there are USB accessories where one end is hard-wired into the accessory itself, such as a mouse or keyboard.

USB-B

This type of connector is almost exclusively found on accessories and smaller devices such as smartphones, tablets, portable hard drives and printers. As the image below shows,  there are several versions of USB-B. 

Full-size USB-B and USB-B 3.0 ports are typically found on printers and older external hard drives. They are different shapes, and USB-B 3.0 cables have a blue connector. 

Mini USB-B is typically just known as Mini USB, and is found on older handheld devices and accessories such as USB microphones. 

Micro USB-B is probably the most common USB-B port, and is found on older smartphones and tablets, as well as newer budget models. Meanwhile, Micro USB-B 3.0 looks like two connectors in one, and is used for devices where higher speeds are important, such as external hard drives. These are becoming less common and are being replaced by USB-C.

USB-C: The new standard

USB-C is the latest generation of USB, and the first USB type that is both reversible (connectors can be inserted either way up) and can appear on both ends of a USB cable. 

They can be used for anything from charging a laptop or phone to connecting to a monitor or powering a large external storage device. 

As we mention below, USB-C is the only connector designed to manage speeds up to the USB 4.0 standard, though simply having a USB-C port does not guarantee this. 

We expect USB-C ports to increasingly replace USB-A ports on modern laptops, and indeed some laptops, including the latest MacBook Air and MacBook Pro, already exclusively use USB-C ports. It’s worth keeping an eye on this if you want your laptop to work with your existing wired devices. 

Charging a laptop with USB-C

Many laptops now come with USB-C ports that are also used for charging in a similar way that most modern smartphones are charged with USB-C. 

There is no hard and fast way of knowing how much power a given USB-C port or cable will accept without checking the manual of the product. This is particularly important now as so many laptops can only be charged over USB-C, but you will only be able to charge them at decent speeds with the right cable and charger. 

It makes for a somewhat hit-and-miss approach to charging, so while it is handy to be able to charge a laptop with the same cable that comes with your phone, in reality this is likely to be a slow and compromised experience. The upside is if you're running low and only have a USB power bank to hand, you can very slowly charge your laptop using it. It's likely the laptop will only gain charge if it's not switched on while you're charging it, unless you have a very powerful battery pack.

It is worth noting that just because a laptop has a USB-C port does not mean it can be charged using it. Generally speaking if the laptop has a more standard circular ‘barrel’ charger it can’t also be charged over USB-C. For laptops tested since 2021, our review Tech Specs will mention whether a laptop can be charged via USB-C.

USB 2.0, 3.0 and 4.0: what’s the difference?

Your child’s first steps. A dog catching a ball in slow-motion. A piece of on-the-street video journalism. These are all things you want to share online as soon as possible, but if you’ve captured them on your camera and need to upload it via your laptop, you might find yourself waiting around for the file transfer to complete. 

That’s why it’s important to ensure you’re using the best USB port that your device will support. As a simple rule, the bigger the USB version number, the faster the speeds. Below, we've explained the differences between USB standards.

Before we move on, though, it’s important to state that two devices that have USB connections should be able to talk to one another no matter what connection speed either device has. As long as you have a cable with the right connections at either end, you’ve won half the battle.

The two devices will simply connect at whatever speed the slowest device is capable of. So if you have a laptop with a USB 2.0 port connected to a hard drive that can deliver speeds up to USB 3.0 standards, your speeds will be limited to that of the USB 2.0 device. 

The one exception to this plug ‘n’ play rule is where the device you’re connecting to is also powered by the USB port. If your USB port doesn’t match the power requirements of the device, it won’t work at all. Consult the manual of your accessory to see what it needs in terms of power.

USB 1.1

This is the very first consumer USB standard and doesn’t appear on any modern devices. It has a maximum speed of 12 megabits per second (12Mbps).

USB 2.0

Still relatively common on cheaper laptops, this standard supports up to 480Mpbs speeds. This is also the slowest USB connection standard to be supported by USB-C connector

USB 3.0, 3.1 and 3.2

This is where the relative simplicity of USB numbering starts to go awry. In short: 

  • USB 3.0 supports 5Gbps (5,000Mbps) 
  • USB 3.1 supports 10Gbps
  • USB 3.2 supports 20Gbps. 

USB 3.2 is only supported by the USB-C connector, while USB 3.0 and 3.1 also work with the classic USB-A connector. 

USB 4

The very latest standard, first introduced in 2019, supports speeds up to 40Gbps. This standard also supports the separate (but related) Thunderbolt connection, which we’ll talk about later. It is also exclusively supported by USB-C, with no other connectors providing these speeds.

What USB connection standard do my devices use?

Whether your device’s ports are USB-A, USB-B or USB-C will be (relatively) obvious from their size and shape, but to find out what connection standard they use, you’ll need to consult  the online manual or spec sheet of your device. 

You might notice that some of your USB ports have different colours and symbols on them. Indeed, there are colour and logo standards for USB ports, but not all computer makers seem to follow these standards. 

There are also stickers and logos that manufacturers can use, but they do not do so consistently. The manual and online specs are the only reliable source of truth.

What are Thunderbolt ports? 

The ports on the very latest MacBooks are described as ‘Thunderbolt / USB 4’. Thunderbolt and USB-C look exactly the same, but they operate slightly differently. 

What this means in practice is that if you’re buying an accessory that uses Thunderbolt connections, such as high-speed storage or a monitor, you should use the supplied cable or a certified Thunderbolt cable. If you’re plugging in a regular USB device, you can use either a USB-C cable or a Thunderbolt cable. 

Apple’s support website has further information about USB-C vs Thunderbolt.

What is an HDMI port used for? 

After USB, HDMI is the second-most common connection type you’ll find on a laptop; HDMI ports are used to connect computers to TVs or computer monitors. The majority of laptops with HDMI have a single port. 

Some all-in-one PCs have two HDMI ports: one for connecting to a second screen (an output), and one for turning the all-in-one’s screen into a monitor for another device (an input), such as a laptop or games console. 

Are there different types of HDMI port?

If you read the USB section above and thought that was complex, then HDMI is a similar kettle of fish. As with USB, HDMI ports come in different shapes/sizes and have different connection standards, which  are independent of each other. 

As with USB, simply connecting two HDMI devices together should always work in some way or another, but you’ll be limited by the capabilities of the inferior device. This means you may not get the best picture quality that either device is capable of. 

For example, if your laptop’s HDMI port is only capable of delivering a Full HD picture but your TV is 4K, you’ll be limited to a Full HD resolution when you connect your laptop to that TV. 

Unlike USB, we don’t really need to get into the nitty-gritty of different HDMI connection standards. The reason for this is because all laptop manufacturers state the capabilities of their devices on the specification sheet. 

If you have an older laptop, it might be a case of trial-and-error to find out what it’s capable of, but almost every laptop bar the absolute cheapest models from several years ago will be capable of Full HD at bare minimum. 

Most modern laptops will support 4K from their HDMI ports. Consult the manual, online specification sheet or customer service to confirm this.

For more, read our guide to HDMI cables and our explainer on 4K Ultra HD

HDMI connections: full-size, mini and micro

While you don’t need to worry too much about HDMI connection standards, you do need to keep an eye on the size of the HDMI port that your computer might have. 

The most common HDMI port is the full-size port, but there are two more that you’ll occasionally see on thinner laptops. These are the Mini and Micro connectors. Ensure you check which is which before you commit to buying an HDMI cable.

Some laptops that only have USB-C ports and no HDMI ports may be compatible with HDMI anyway if you buy a USB-C to HDMI adapter. As of 2021 we test all computers with USB-C ports to find out whether they work with a USB-HDMI adapter and you can find the results in our laptop reviews’ Tech Specs.

HDMI adapters

If your computer has an HDMI port but your monitor does not (or vice versa), then you’ll need to buy an adapter to slot into the connections you do have.

If your monitor doesn’t have HDMI it will likely have either a VGA or DVI port that you can plug the adapter into.  

An HDMI to VGA adapter lets you connect a newer laptop to an older monitor

In the case of HDMI to VGA, you’ll need to ensure you also have a spare USB port on your laptop to plug the adapter into, because these adapters require a small amount of power to work.

If your computer only has a VGA port  but your monitor only has an HDMI port, you will need another form of adapter that works in reverse to the adapters mentioned above. 

Do I need an Ethernet port?

Ethernet ports allow you to connect your computer directly to your router via a cable for a faster and more stable internet connection than is often available over wi-fi. Keep in mind that you can’t connect your laptop directly to your phone/broadband line; you need a router to make sense of all the data before it is sent to your laptop.

Most laptops don’t have Ethernet ports because the connectors required are fairly large. Laptop makers prefer to deliver thin devices so they often skip including this handy port. 

Desktop computers, meanwhile, almost always have Ethernet ports, and may not always allow connection over wi-fi.  

Read our guide on how to buy the best desktop PC for more on what to look for in a desktop computer.

Is Ethernet faster than wi-fi?

Typically, yes. The theoretical maximum speed of an Ethernet port is 1,000Mbps (1Gbps), while most wi-fi connections are considerably slower. A wired connection will also have a lower ‘ping’ rate (the time it takes for data to be sent and received), and allow for better gaming and video chatting experiences without lag and stutter.

Wi-fi connections can be affected by all sorts of things, including other electronic devices, walls and the distance to your computer. 

If you’re able, wiring up your computer to your router is likely to give you the best connection, although in many cases this won’t be practical. But if your desk happens to be next to your router, consider plugging in if you can. 

Even if your computer doesn’t have an Ethernet port, USB-Ethernet adapters are cheap and work on any laptop with a USB port. 

Find out more on routers with our Wi-fi router reviews

What are SD and microSD card readers?

Many laptops come with SD card readers or their smaller siblings, microSD, built into the frame. The most common use of SD cards is in digital cameras, but they can also be found in other media recording devices such as camcorders and audio recorders.

If your laptop only has an SD card slot but your camera, for example, only takes microSD cards, you can buy an SD to microSD card adapter. This is basically an SD card with a slot to pop in a microSD card.

If you only have a microSD card reader but have a full-size SD card you want to use, you could buy a USB to SD card adapter, or buy a new microSD card with an SD card adapter so you can easily put the same card into multiple devices.

If your computer has very little storage, you can use your microSD card slot as a way of expanding its storage. This could be a good way of storing files you don’t use so often. Bear in mind, though, that  SD cards are relatively slow compared to built-in computer storage, so shouldn’t be used for storing large, frequently-accessed files or programs.

How can I add more ports to my computer?

There are lots of ways to add ports to your computer. We’ve mentioned a few single-purpose adapters above; as long as you  have a USB port to plug it into, you can find an adapter for practically anything.

If you want to add lots of ports at once, you’ll want to find yourself a dock or hub that includes all the ports you need, be it Ethernet, an SD card reader or just even more USB ports.

This is especially handy if you have a dedicated desk with a separate, wired mouse and keyboard, but don’t want to have to spend time connecting and disconnecting them every time you want to take your laptop elsewhere. With a hub or dock, you simply have to connect one cable and away you go.

Adapters come in all sorts of shapes and sizes If your computer has any USB-C ports, it’s best to buy a USB-C hub as this will allow for the fastest speeds from the devices attached to the dock to the computer itself.

You can also buy monitors with USB hubs built-in. This lets you have your bits and bobs connected directly to the monitor, and all you have to do is plug in a single USB cable leading from the monitor to connect them all at once.

Some USB-C docks will also have HDMI connections, but keep in mind that this will only work if the USB port you’re connecting to supports display connections. Check with the specifications sheet of your laptop first to see whether it works.


Read our guide on how to buy the best laptop to nail down the features you need – from ports to pixels.



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