How-To Geek

The HTG Guide to Adding an Extra Monitor to Your Laptop

Multi-monitor setups on desktop machines are pretty straight forward: if you have the ports and the appropriate cables you’re in business. Adding extra screen space to your laptop, however, can be quite a bit trickier. Read on as we show you how to enjoy extra screen real estate on your laptop no matter what your port situation and with a variety of secondary screen possibilities including repurposing old monitors, tablets, or even buying a portable USB-driven display.

Why Do I Want To Do This?

Before we even begin to explain to you why you want extra screen space, we’ll need to clearly declare our bias on the matter: most of the workstations at How-To Geek are sporting two or more monitors (and the station this particular article was written on sports three). While some people prefer the focus of having only one thing open at a time on their single monitor, we really love having room to spread out, place documents side by side, park communication windows on one screen while we work on the other, etc.

If you’re looking to do the same, to add a little space to your laptop rig to park extra windows, leave notes open, or otherwise enjoy the kind of dual-screen (and bigger) screen space that is  typically reserved for desktop users, this is the tutorial for you. We’re going to start with the cheapest (and, coincidentally, least portable) options and then work our way up to more expensive and significantly more portable solutions.

Linking a Standard Desktop Monitor to Your Laptop

It would be easy to think that laptops no longer came with external display ports looking at the sleek and narrow bodies of modern laptop and ultrabook-style machines. Throughout the 1990s and well into the 2000s it was common (and expected even) to see a big chunky blue VGA port sticking out the back or side of any laptop you came across.

You’d be as hard pressed to find a laptop today with a VGA port as you would to find one with a parallel port: the days of analog peripheral connections are long gone in mobile computing aside from a legacy-oriented build here or there. That doesn’t mean there’s no way to plug in a monitor to your laptop. The new standard on laptops for external displays is the slender and easily overlooked HDMI port. (Seen in the photo below on the left.)

Laptops with HDMI-out ports can be be easily connected to any external monitor (be it an actual monitor or a HDTV) that accepts HDMI inputs. If you have a computer monitor that doesn’t have an HDMI input port but does have a DVI port you can easily use an inexpensive HDMI to DVI cable adapter to bridge the gap as both the HDMI and DVI signals are fully digital and require no transcoding or the like.


The majority of HDMI-DVI adapter cable product descriptions make it sounds like they’re intended to link DVI sources to HDMI screens (such as a DVI output on a video card to an HDMI-enabled monitor or HDTV) but don’t worry they’re bidirectional just like a regular old HDMI cable. Similar adapters exist (and at a similar price range) to convert DisplayPort (another digital video port format) to HDMI or DisplayPort to DVI if that’s the video port available on your laptop.

In the above photograph we have the laptop hooked up to an ASUS desktop monitor (for the curious: it’s the VN248-P, a great value that can be found on sale for around $130 practically every other month) with the laptop screen displaying our Beginner’s Guide to Minecraft series and the desktop monitor displaying Minecraft. We used Minecraft to test every external monitor setup in this series as a way to track movement and frames per second when it really matters (e.g. playing a game) as oppose to simply loading a static web page (which even the cruddiest monitor setup would have no problem with). Playing Minecraft on the second monitor was a smooth experience with no drop in FPS.

When you plug in the monitor most operating systems and laptop hardware will automatically detect it (and, at minimum, start mirroring your laptop screen to the secondary screen). Mirroring is typically the default for laptops as this way they’re ready to go when hooked up to a projector for a presentation. Use the Fn keys on your laptop (usually Fn + F3) to switch between view modes or use the display panel for your OS to make the adjustments once the HDMI cable is connected.

If you have a rare laptop that is so slimmed down it doesn’t even have an HDMI port, that doesn’t rule out the ability to use a traditional monitor. You’ll simply need to pick up a USB-to-HDMI adapter. These adapters typically run around $50 (this basic USB 3.0-to-HDMI unit from Cable Matters is $48 and includes a HDMI-to-DVI adapter). You can find adapters that will shift from a digital HDMI signal to a VGA signal, but loss of signal quality in the shift from digital to analog (by the very nature of the process and by no fault of the adapter manufacturer) is pretty unbearable. Stick to a fully digital signal wherever and whenever possible.

Note: If you’re shopping for a USB adapter we strongly recommend really poring over the reviews and comments for the model you’re looking at. Many highly ranked adapters, for example, have poor driver support for the latest OS releases. A three year old adapter with hundreds of 4 star reviews left by Windows 7 users isn’t much good to you on Windows 8.1 if the manufacturer hasn’t updated the drivers.

The obvious primary downside of the setup outlined above (whether or not you have to shell out for a new cable or adapter) is the portability issue. Adding a nice desktop monitor to your laptop will generally double (or even triple) your screen real estate but only when you’re sitting at your home or office desk. Packing up even a slim desktop monitor and taking it on the road for business or to the library is rather impractical.

Linking a USB Monitor to your Laptop

If you want the screen space of a traditional monitor mated with the kind of portability you can slip into your laptop’s carrying case, there’s a whole sub-class of monitors designed just for you. These products exist in a sort of limbo between full-size monitors and tablet screens in terms of screen size, resolution, and contrast.

For the last few months we’ve been palling around with an AOC e1659wu, a highly rated entry in the USB-monitor genre. Because the AOC does what it does so well, we’ll use it to highlight exactly what you need to look for in a USB monitor.

While the AOC isn’t plug ‘n play, it is pretty easy to install. You’ll need to pull the drivers off the included CD-ROM or if your laptop doesn’t have a CD-ROM drive (and not many do these days) you can visit AOC’s support site to grab the drivers. The driver installation package installs DisplayLink drivers and then you simply need to plug in the monitor.

The AOC offers a 16″ spread (15.6″ viewable) and a max resolution of 1366×768. It weighs about as much as our ultrabook (2.6 pounds) but unlike our ultrabook requires no additional power brick (thank goodness for that). It draws all its power via two USB ports (on port for the data and the extra port for extra power). While it’s no fun to lose two USB ports in one swoop it’s a lot less fun to pack an extra power brick so we’re not complaining.

The USB component of the AOC design is important: USB 3.0 offers a significant increase in available bandwidth over a USB 2.0 setup. You can actually pickup the older version of this very monitor in USB 2.0 (and save $40 in the process) but if you’re planning on using it for video or even a casual video game, we’d strongly recommend skipping the USB 2.0 model and picking up the USB 3.0 model. Not only is the newer model improved in a variety of small ways (it has more resolution options, a nicer stand, and a VESA mount if you wanted to attach the second monitor to an articulating arm, stand, or such) but the upgrade to USB 3.0 radically improves response time. Unless you only  intend to use your secondary monitor for very low-bandwidth applications like a chat window, USB 3.0 is a must.

If the primary concern with a USB monitor is available bandwidth (all the excellent styling in the world can’t make up for a laggy screen) then the screen brightness, contrast, and the overall styling of the unit are second in line. You can easily adjust the brightness and contrast from the Windows System Tray by selecting the AOC icon and using the settings menu. We have two minor complaints about this process: one, there’s no reason not to make this a hardware-based process via buttons on the case (there are no buttons to speak of on the AOC monitor) and two, we wish we could make it just a little brighter. The first complain is a pretty valid one and the second, we understand, is more difficult to fix if the engineers want to keep the monitor running off USB power.

Although the glossy screen made it difficult to photograph (and we don’t care much for glossy screens in general) the screen on the AOC was sharp and the glare when actually using the monitor was minimal.

The stand worked great; you could adjust it anywhere between closed and fully open and the mechanism stayed firmly where you left it. You can see the VESA mounts in the photo above which are, in our opinion, a nice little option to include. Most people won’t use them but if you end up wanting to mount your portable monitor to a swing arm or other mount point it’s nice to have them there.

The final noteworthy design feature is that you can easily rotate the monitor (and it even senses the rotation and changes accordingly). Laptop screens are almost universally widescreen now but there are still so many things we look at that are portrait in orientation (like most web pages, documents, etc.). It’s handy to flip your AOC monitor around and use the space more efficiently.

We’ll admit that we didn’t expect a whole lot from a USB-driven monitor, but the AOC really delivers what it promises: low-fuss and very portable screen real estate for laptop users.

Linking a Tablet to Your Laptop

If you read over the last section and thought, “That sort of looks like a giant tablet sitting there,” you’re on to something. It’s not particularly economical to go out and buy a tablet just to serve as a secondary monitor but if you already have a tablet like an iPad or larger Android tablet you wish to repurpose (even on just an as-needed-basis) as a second monitor, there are a variety of ways you can do so.

Several of the most popular applications on the market for both iOS and Android, such as Air Display and iDisplay, rely on the tablet and your laptop (or any host computer) sharing the same Wi-Fi network. This is an irritating design choice for a variety of reasons. First, the setup is completely wrecked by routers with AP isolation turned on (a feature many coffee shops, libraries, hotels, etc. use on their Wi-Fi networks to ensure that every client can talk to the router and the greater internet but not to each other); so the places you’re most likely to use the feature are the places most likely to break the feature. Second, it introduces a lot of unnecessary lag. Third, it introduces a potential security risk; why send all your screen data over the local Wi-Fi node? We get that it’s no-cables convenient but it’s prone to failure, slower, and has a built-in security risk.

Instead, a better way to approach the problem is the same way we approach hooking up a plain old monitor: with a physical cable. To that end, we’re rather fond of relatively unknown app (compared to the aforementioned Air Display and iDisplay) known as TwomonUSB. It costs as much as the other options on the market ($9.99) but it offers the one thing we really want: USB tethering. Instead of relying on a Wi-Fi connection, putting up with lag, and opening ourselves to a potential security risk, we can just plug our iPad right into to laptop as seen in the photo above.

All you need to get the whole system working is the TwomonUSB app on your computer, the companion computer app (it will prompt you to download it when you launch the app on your tablet), and an appropriate tether cable.

Like in our previous tests, we browsed the web on the laptop and played Minecraft on the secondary screen. No issues at all and our Minecraft FPS actually crept up a little (presumably because the resolution of the tablet is much lower than the resolution of the laptop screen).


Although it’s easy to think you’re stuck with a single laptop screen there are plenty of options available. Assess your needs, your budget, and how portable you want your second screen to be and select the best fit from our tradition monitor, USB monitor, and tablet-as-second-screen configurations.

Jason Fitzpatrick is warranty-voiding DIYer and all around geek. When he's not documenting mods and hacks he's doing his best to make sure a generation of college students graduate knowing they should put their pants on one leg at a time and go on to greatness, just like Bruce Dickinson. You can follow him on if you'd like.

  • Published 08/7/14