What Is A USB Hub?

What Is A USB Hub?

Last Updated on by Daniel Lawrence

Have you heard of the term USB hub? If you haven’t, you will in this guide, and if you have, you’ll learn more about what a USB hub is. Read through this guide, and by the end of this guide, you should be conversant with the term USB hub.

What Is A USB Hub?

A USB hub is a handy way of adding additional USB ports to a setup. They’re the USB version of a regular plug extension lead, converting a single USB socket into a hub of them. You plug it into your computer, then use the additional ports to use mice, keyboards, and other USB devices all from a single port.

Much like extension leads, USB hubs also have limitations. You can’t load too many power-hungry devices onto it, else difficulties arise. However, if you want to use a keyboard, mouse, and a phone charger on one USB port, a hub can achieve this.

USB hub operation

By definition, a USB hub has what is termed one ‘upstream port’, i.e. the one to the host, and several ‘downstream ports’ – these are connected to further hubs or peripheral devices/connections.

During the operation of most systems, the hubs are transparent and they do not appear on any system visible mapping. Data that is received from the upstream port, i.e. from the host is broadcast to all devices that are attached to the downstream ports, but data from a downstream port is routed only to the upstream port and the host.

With the introduction of USB 3, a capability of Point to Point routing has been introduced whereby a routing string sent in the data packet header enables the host to direct the data to a single destination port. This decreases the level of data on the USB ‘network’ and it also serves to reduce power consumption.

One additional advantage of using a USB hub is that it can provide a length increase within the system. USB cables are limited to 3 meters for low-speed USB 1.1 devices, etc. A hub can be used as an active USB repeater to extend cable length for up to 5-meter lengths at a time.

Points to note when using a USB hub

USB hubs are normally plug-and-play and work very easily straight out of the box. They have been developed to a stage where there is normally little to do in setting them up and using them.

However, when using them there are a few useful pointers to note to ensure that the best performance is achieved.

  • Use the highest USB version hub where speed is important:

Often high-speed connections may be required via the USB hub. For example, in some cases an Ethernet connection to the Internet may be made via the hub, or a large capacity disk drive – these connections should be made via the fastest USB hub available.

Use USB 3 instead of USB 2 for these. There may be an instance where a USB 2 hub and a USB 3 hub are available, or there may be a choice of USB 2 and USB 3 ports on a hub. Always use the fastest ports where high speed is needed and use the slower ports for mouse or keyboard connections, etc.

  • Higher power peripherals may require a dedicated USB slot:

In some instances, peripherals need a reasonable level of power. There may be instances where the peripheral does not work via the USB hub but needs a direct connection or the use of a powered USB hub. When USB devices like CD/DVD drives or disk drives do not work via the hub, then check whether they work using a direct connection.

  • Some hubs may become warm:

With the level of functionality contained within some of the more complicated USB hubs, large amounts of processing are required. This means that the hubs will consume power and will become quite warm. Be aware that some USB hubs can run quite warm and as such, they should be sufficiently ventilated to prevent them from becoming too hot.

  • Connect to high-speed USB port on computer:

Some computers have Type-A ports – these can be USB 2 or USB 3. It is best to ensure that the USB hub is connected to a high-speed port so that the best performance is obtained. If the hub is connected to a USB 2 port, then this will limit the performance to that of USB 2. Connect it to a USB 3 port then this allows for USB 3 performance.

  • USB ports can be chained:

As there are often limited ports on many devices, and also some USB hubs have limited ports, they can be chained, i.e. plugging one hub into another. However, be aware of the power limitations because it is very quickly possible to overload any power availability.

Reasons Why You Might Need a USB Hub

Now that we’ve explored what a USB hub is used for, let’s explore some use-cases where you might want to grab one.

  • You Want to Increase the Number of USB Ports on a Laptop

While there are some laptops out there that come with a bunch of USB ports, many only have two. This restrictive number of ports really isn’t great in our current USB-saturated landscape. If you use a USB keyboard and mouse, you don’t have any spare ports to charge devices, hook up an external hard drive, or connect a printer.

Of course, this may be fine depending on what you do with your laptop. If you’re always on the move and you don’t need a mouse or a keyboard, you won’t have this problem. Maybe you’ll just need to charge your iPad and use an external hard drive or a two-factor authentication key.

However, if you use a laptop as your primary computer, or regularly do more than just sending emails and writing while you travel, a small USB hub might be a really useful tool.

  • You Want to Charge a Multitude of Devices on One Port

A USB hub is great for charging a number of different devices at once. While unpowered USB hubs need to be plugged into your computer to do that, powered hubs instead use the mains. This lets you charge as many devices as you like, regardless of if your computer is on or not.

USB hubs are the perfect companion for someone with lots of power-hungry USB devices. From phones to tablets to desk gadgets, a USB hub can meet the needs of any gadget that needs USB power. It’s also convenient that you don’t need to hunt for a spare mains plug; just plug everything into the same hub.

  • You Want to Move a Lot of Data Between USB Devices

This is one of the rarer kinds of USB hub uses, but it’s still very valid. If you find yourself in the situation of needing to move a lot of data between a bunch of different devices, a USB hub can be very useful.

If you want to back up photos from your computer, tether your mobile phone to use cellular data on your PC, download images from your camera, print some documents, and upload music to your iPad, a high-quality USB hub can help you do all of that at the same time.

Again, this admittedly isn’t a common situation for most people, and it would only warrant a USB hub if it happens on a regular basis. However, if you do find yourself moving data like this a lot, investing in a USB hub is going to make your life easier.

Types of USB port hubs

There are two main types of USB port hubs: powered hubs and unpowered hubs.

  1. Powered USB hubs

Powered USB hubs provide their own power supply for devices. Typically, when you connect a device to your computer via USB, the device draws upon your computer’s power to function.

Powered USB hubs come with their own power source and provide power for your connected devices so your computer doesn’t have to.

Powered hubs are great if you’re connecting USB devices that operate on higher voltages. These devices may include:

  • Large external hard drives
  • Printers
  • Scanners

Both powered and unpowered port hubs plug into your computer via a single USB port. There’s only so much power that can be transferred through a single port, though. If you have several high-voltage devices connected to an unpowered hub, the hub will not be able to transfer enough power from your computer to power all those devices at once. It just can’t draw enough power through the single USB. There’s a good chance that one or more of the connected devices might not function properly.

Powered hubs alleviate this problem. Each device that’s connected to a powered port hub draws power from its own USB connection. As a result, one USB port doesn’t have to dispense power to multiple devices simultaneously. This is why powered hubs are crucial if you’re going to be connecting larger and more intensive hardware.

  1. Unpowered USB hubs

Does that mean you should avoid unpowered USB hubs? Absolutely not. Unpowered hubs are perfect if you’re going to be connecting smaller devices, like:

  • Keyboards
  • Mice
  • Smartphone chargers
  • Flash drives
  • Gamepads

Furthermore, unpowered hubs are more portable than powered hubs. Unpowered hubs are more compact and they don’t need to be plugged into a power outlet (which also means they don’t have the additional power cables that you have to lug around). They’re also a little more budget-friendly.


Technology enthusiasts and gadget fans need as many USB sockets as they can muster, but some computers and laptops have a fairly low number of them. If you’re always unplugging devices to make room for others, the USB hub is a fantastic companion. Still, they’re not perfect; in some situations, there are solutions that work better for you.