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Oct 182015
My new Asus external USB monitor alongside an older Dell laptop.

My new Asus external USB monitor alongside an older Dell laptop.

We all experience (at least!) two problems when traveling.  The first is we become extremely pressured, time-wise.  With the travel itself, and the activities we’re doing on our travels, the time we have for all the regular computer activities we do every day is massively reduced, so productivity becomes even more important.

And the second thing?  We drop from maybe two or three or four nice large 22″+ sized monitors, each with 1920×1080 or better resolution, down to a single tiny laptop screen – commonly 13.3″ – 15.6″, occasionally 17″, and perhaps with a much lower resolution.  This was once unavoidable, but now is unnecessary.

Why You Should Have Two Screens (Everywhere)

Although there can be some subtle downsides (ie too much screen space can mean too many distractions), in general, it seems that having two or more screens will boost most people’s productivity, on most tasks, by up to 50%.  Clearly this won’t happen if all you’re doing is watching movies or updating your Facebook page, but for many other computer uses, more screen area means more productivity.

Here’s a widely cited study by Microsoft that, while now somewhat dated, supports these findings, and a second article from Viewsonic that expands on the Microsoft research.  Yes, as a screen manufacturer, Viewsonic has a vested interest in selling more screens, but the studies they cite are persuasive.  Bottom line – a big screen is better than a small screen, two small screens are better than one large screen, and two large screens are better still.  Further benefits flow from three and more screens, but particularly when traveling, we quickly reach the point where the hassle factor exceeds the benefit when going above two moderately sized screens.

Never mind the academic studies.  I know this to be true from personal experience.  The day I went from one to two screens was one of the most transformative experiences I’ve ever had.  When people say to me ‘I don’t know how you do everything you do, David’, one of the explanations is good use of multiple screens.

There’s nothing we can do to make more time in our day, but there are some easy and essential things we can do to achieve more in the time available to us.  Adding a second computer screen is one of the most effective – and one of the most cost effective – ways of massively improving our productivity.

But First – The Easiest Best Travel Productivity Boost of All

For most of us, the first thing we should do is to buy an external mouse, rather than struggle with the trackpad built into the laptop.  An external mouse is small, lightweight, and inexpensive and so much easier to use.  Amazon sell them for $10 or less.

We prefer a traditional cord connected mouse rather than a wireless mouse – they are less hassle and it is one less set of batteries to worry about, but the choice is yours.  If you prefer a wireless mouse, the extra cost these days is surprisingly minimal.  Amazon sell them for almost no more than the cost of a wired mouse.

There’s no better way to get an instant and easy productivity boost than adding a ‘real’ mouse to your laptop.  The only downside is a requirement to have a surface to place the mouse on – a problem if you’re truly balancing the laptop in your laptop, difficult with a coach class tray table, easy in most hotel rooms.

But what else can you do?  Easy – add a second portable screen.

Modern External Screens Truly are Practical and Portable

The transition from old fashioned huge heavy glass CRT monitors to modern flat panel LCD displays and the implications of this wonderful change have gone largely unnoticed by most of us.

But what it means when we travel is that something that was formerly unthinkable is now completely practical – we can now sensibly plan to travel with a second external monitor for our laptop (note that these external monitors also work with some types of tablets such as the Microsoft Surface, too).  Most portable screens weigh less than 3lb, and some weigh less than 2lb.  That’s comparable to the weight of a tablet or a hardback book, or, if you prefer, less than the weight of a fifth of your favorite tipple.

There’s been a matching ‘invisible’ improvement in the practicality of external monitors for laptops too.  Most of these external USB connected monitors are ‘plug and play’ – just connect them to a USB port, and there you are with instant immediate two screens.  This makes use of a new technology called DisplayLink – there’s no need to dwell on what it is or does, because it is all automatic/automagic and does its stuff behind the scenes.  The net result is that most modern laptops can support up to as many as six screens!

Another improvement is that the best of the external monitors draw so little power that they don’t need an external power supply – they just take the power from the USB port.  Some that need additional power simply connect to any external USB charger via a second cable.  That cuts down on the clutter of power bricks and cables we otherwise might need to travel with.

Choosing a Portable External Monitor

Any external monitor you travel with needs to be light and rugged, with as large a screen as possible but in as small a form factor as can be managed, and of course, light rather than heavy.  Let’s talk about the things to look for.

General Portability

The smaller the overall size of the monitor, and the lighter it is, the easier it will be to travel with.  There’s no point in choosing a ‘perfect’ monitor if it is so big and bulky that it is left at home and you seldom travel with it.

You should think carefully before choosing a screen that weighs over 2 lbs.  There are plenty of excellent choices weighing less.

There are two more portability issues to consider.  The first is whether the screen has any sort of protective carry case with it.  If it doesn’t, you’ll definitely want to create some type of protective sleeve for it.  The second is what type of stand it comes with to have it alongside your laptop.  Some stands allow the screen to be in either portrait or landscape mode – we don’t see much value in this, but if it is important to you, then you should ensure your screen offers it.

Screen Size

While in theory, bigger is usually better, our suggestion is to consider a 15.6″ sized screen (sometimes optimistically described as a 16″ screen).  There are both smaller and larger sizes available, but we feel 15.6″ to be the best compromise between screen size, overall size, cost and weight.  It is also the most common size offered.

One other thought is to choose a screen that is similar in size to your laptop screen so as to make it easier to flow work over and between the two screens.

Screen Resolution

Again in theory, more pixels are usually better than fewer pixels.  But there is an exception to that – when you have two screens, you want to have a reasonably consistent viewing experience on both screens.  You don’t want something you’re looking at on one screen to suddenly grow or shrink if you move it over to the second screen.

Many of the things we have displayed on our screens are internally described and sized in terms of pixel dimensions.  So if you have an object that is described as being 100 x 150 pixels in size, it gives for a ‘smoother’ experience to you if it is visually the same size on either screen.

The easy way to avoid this is to get a screen of the same physical size and same resolution as your laptop screen.  If this isn’t possible or desirable, the next consideration is to choose a second screen with similar pixel density to that of your laptop’s main screen, as measured in pixels per inch (PPI).  (Note that it is usually possible, within Windows, to vary the magnification of text and other content on each different monitor, so this can be a helpful adjustment when you have vastly different pixel densities.)

It is not always easy to find what the pixel density is for a screen, so here is a table of typical screen sizes and resolutions, and the pixel density for each such size/resolution combination.  We also include a column for a typical 24″ sized desktop monitor, to give you a further comparison, but are definitely not suggesting you should pack a full size 24″ monitor in your suitcase when traveling.

Don’t obsess over exactly matching the pixel densities of your two screens, but it is one factor to consider when deciding what might be the best screen choice for you.

13.3″ 14″ 15.6″ 17″ 24″
1280×720 110 105 94 86 61
1280×800 113 108 97 89 63
1280×1024 123 117 105 96 68
1366×768 118 112 100 92 65
1400×1050 132 125 112 103 73
1440×900 128 121 109 100 71
1600×900 138 131 118 108 76
1600×1200 150 143 128 118 83
1680×1050 149 142 127 117 83
1920×1080 166 157 141 130 92
1920×1200 170 162 145 133 94
2048×1536 192 183 164 151 107
2560×1600 227 216 194 178 126
2880×1800 255 243 218 200 142


If you have some other screen size or resolution, this excellent page helps you to calculate its pixel density.

Screen Image Quality

There are several measures of screen image quality that are slightly relevant, particularly when dealing with portable screens which have to incorporate more compromises within their designs (to minimize weight and power consumption) than do regular desktop screens.

Here are explanations and recommendations on five measures of screen quality that you’ll sometimes see quoted

Screen colors – this is most likely going to be 262,000 colors, or 18 bit color resolution.  In comparison, most desktop screens support 16.7 million colors or 24 bit color resolution.

This sounds like a huge difference, but the chances are you’ll not even notice.  It is not a very important difference for anyone other than a graphics professional who needs a wide-gamut calibrated screen.  If you don’t know what wide-gamut is, then you absolutely don’t need it!

Brightness – This is usually measured in cd/m2, and typical values range from 150 – 300.

More is better than less, but even a 150 cd/m2 value is probably acceptable for most ‘in hotel room’ type purposes, although probably insufficient if you’re wanting to use the screen outside in the bright sunlight.

Contrast – This tells you how many different shades of grey you can see between full white and full black (and the same for other colors too).  Contrast is usually expressed as a ratio, and values between 300:1 and 1000:1 are common.

More is definitely better than less, and in particular if you are using your external screen to watch movies (or possibly play games) on, you’ll notice a difference, where lower contrast screens lose detail in the shadows and highlights.  But for reading text and web browsing, this won’t be an issue at any value.

Note that some screens show contrast ratios in excess of 1,000,000:1 – this is a ‘dynamic’ contrast ratio, a bit like the enhanced dynamic range setting on a modern camera – it is a somewhat good thing to also have, but it isn’t ‘real’ contrast, it uses a visual ‘trick’ to make the contrast seem better than it is, and the real underlying contrast measurement is the one that is most important.

Response time – This tells you how quickly the screen can display an image, and also is one factor in the screen’s refresh rate as well.  Response times are measured in msecs, and less is better than more.

Most screens have a refresh rate of at least 60 Hz, which means their response time needs to be less than 16.7 msec.  It is common to see response times in the 5 – 10 msec range, so this is usually not a problem.

Viewing Angle – Remember how it used to be you needed to be directly in front of a screen?  If you moved even a little bit off center, it would darken and the image would lose detail?  A screen’s viewing angle tells you how far off center you can be and still see the same bright image.

But this is potentially a very misleading measurement, because almost never are you told how much darker than directly in the middle is deemed to be acceptable when measuring the viewing angle range.  One manufacturer might say ‘it is okay for the screen to be half as bright at the limit of the viewing angle’, another might say ‘the screen can be one quarter as bright’.  Furthermore, some companies quote viewing angle as how many degrees from center, others quote viewing angle as how many degrees from one side to the other – which gives a number twice as large as the other way of measuring.  It is also common for screens to have different viewing angle ranges away from the center for horizontal and vertical shifts, but not all manufacturers give both numbers.

The larger the number (in degrees) the better, but this is not a very important number, because you hopefully can position and angle your second screen to make the viewing angle as small as possible, and much less than the quoted angle for the screen.  Viewing angles are more important when multiple people might be wanting to look at the screen simultaneously.  Look for viewing angles of 130 – 170+ degrees, but these days, the optical distortion of looking at anything from such an extreme angle will become more a limiting factor than the screen’s brightness and viewing angle.

Use a USB External Monitor At Home/In Office, Too

The best thing of all about portable USB connected screens is that they aren’t ‘only’ for use with your laptop while traveling.  Connect them up to your desktop computer, at home or at work, and you get an additional high quality monitor there, too.

It doesn’t matter what the capabilities of your video card might be.  The DisplayLink technology works in addition to your video card, so even if you already have two or more monitors on your computer, you can plug in extra USB connected monitors as well.

Not Just for Work Purposes

Maybe you are traveling with a friend and you both want to watch a movie on the flight.  Having a second screen would mean you could each have a monitor directly in front of you on the plane, rather than awkwardly trying to place your laptop in the middle.

You would then simply duplicate what appears on the first screen to have the exact same thing appear on the second screen.

A similar use could apply if you are driving somewhere with two children in the back of your car.

Do You Need USB 3.0?

In theory, there’s not enough bandwidth in a USB 2.0 connection to drive a high resolution monitor at full speed.  But part of the magic of the DisplayLink technology is how it compresses the data, and so it can work perfectly well on a common USB 2.0 interface as well as on the newer/faster USB 3.0 connections.

I tested my screen on both speed interfaces and didn’t notice any difference.  Maybe if you were wanting to drive multiple screens on one USB port/hub/controller, it would become more helpful to have a USB 3.0 speed connection, but for ‘only’ one external monitor, the USB 2.0 connection works perfectly well.

A Specific Recommendation

I’ve just bought my latest portable screen, and certainly for my purposes, it seems to be the ‘sweet spot’ with all issues optimized, including price/value.  It was not an altogether easy choice to make, because some vendors misquote specifications or mix up the specifications of different models.

This is the Asus MB169B+, with a 15.6″ screen and 1920×1080 pixel resolution.  It claims to be the world’s thinnest and lightest monitor of that size, and with a 1.76lb weight, it probably indeed is.  Amazon sells it for $190.

The Asus screen comes with a wonderfully generous three year warranty (but probably won’t cover damage if you drop it), so there would be little point in buying an extended warranty cover.  It has a sturdy external carrying case, and it is relevant to note that the 1.76lb weight for the monitor does not include the weight of the carry case.  That is of course true of all external monitors, but when you’re considering the complete weight implications of adding a second monitor, you should keep in mind the weight of whatever protective carry-case you add.  The protective case adds almost another pound (14.5 oz).

The protective case does double duty as a stand for the monitor.  Some external monitors have a tab that extends out the back as a support, and the benefit of the tab is it takes up less space on a desk, but the dual purpose case/stand works acceptable well, too.  It also has a couple of thoughtful loops inside to store the provided USB 3.0 cable.

The provided cable is one meter (39″) in length.  Normally that is plenty long enough, because you’ll want to have your second screen close to your built-in screen, but sometimes – such as sharing the same content on both screens for presentation purposes, perhaps – you might find a longer cable gives you more locational flexibility.  I need a longer cable when I have my laptop in its docking station, and the three different external screens I have connected to it are some distance from the laptop itself.  But that’s an unusual application.

There are certainly cheaper external/portable monitors available, but they are all smaller and much lower resolution.  It is common to see 1366 x 768 monitors, which have only half as many pixels on them as does a 1920×1080 monitor (one million instead of two million).  It might make sense to choose one of these low resolution monitors if your laptop’s built-in monitor is similarly low resolution, but not in other scenarios.  In such a case, we’d recommend the $143 Asus MB168B.

It was very easy to connect the external monitor to my laptop (I tried it on two different laptops).  The first time I did it, the computer automatically installed the DisplayLink driver software – presumably taking it from the monitor (it took quite a while for this, so I imagine there was a lot of software), and then after a reboot, the external screen came alive. A right click anywhere on the desktop and then choosing the Display Settings option brought up the Windows settings to configure the two screens so as to match their physical layout with their logical layout, and everything was then good to do.

I chose to update my drivers from the Displaylink.com website, although it didn’t seem necessary to do so.  There is a utility disk with some programs on it that comes with the screen, but it works just fine without it.

I did have an initial issue where the screen would logically switch off after a few minutes of usage.  The problem seemed to be that it was overloading the current capacity of the USB port I had it connected to (it draws right around 0.95 amps of power – some USB ports are only rated for 0.5 amps).  The solution was to switch to a different higher current port, and that completely solved the problem.

If none of your ports have sufficiently high current capacity, you can get a Y splitter and connect an external USB power source to the screen as well.  Here’s a good splitter for only $8.  And if you need an external power source, don’t use a USB hub.  Use a USB charger – this is our current reigning favorite, with six ports, all capable of supplying 2+ amps.


Modern technology – both the DisplayLink software and lightweight low powered LCD monitors – make it practical and affordable to add a second, external monitor to most laptops.

You can expect up to a 50% increase in productivity if you do this.  That boost is beneficial anytime and anywhere, and massively more so when traveling.

The Asus MB169+ costs about $190 on Amazon and seems to currently be ‘the best of the bunch’.  I’m very happy with mine; the chances are you’ll be very happy with yours, too.

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  4 Responses to “Add an External USB Screen to Your Laptop When Traveling”

  1. I bought the AOC external USB monitor. No matter what I tried I could not make it work with my 2010 Lenovo W510 running Windows 7.

    • Hi, Rich

      I’d looked at AOC monitors too. The company generally has a good reputation, but I noted their pricing was slightly higher than Asus with no benefits associated with the higher price and so chose Asus.

      I’m surprised you had a problem, because DisplayLink is usually a moderate no-brainer. Did you speak to AOC support? Were you giving the monitor sufficient power (that would be my first guess about potential problems).

  2. […] Add an External USB Screen to Your Laptop When Traveling (The Travel Insider). My rule is to never have a job that requires 2 monitors. […]

  3. I wouldn’t give up my Logitech wireless mouse (M705) for anything. Yeah, it’s a full-sized mouse (but no hand fatigue!) and a single AA battery has lasted over a year now with regular use (I use it at home and on the road). Why is it indispensable? It has 3 buttons on the left side, 2 thin ones near the top and the left side of the housing acts as a 3rd, which I set to Copy, Paste, and Cut, respectively. The scroll wheel also tilts left and right for 2 more buttons, which I set to Backspace and Delete, respectively. The ability to perform all these basic text editing functions without having to take my hand off the mouse is HUGE.

    P.S. Yeah, I have an Asus MB169B+ too, and agree with all your positive comments.

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