Have a look at the image below, this is how Youtube will look when someone opens on high resolution screen.There are empty space on both sides and I have checked this with many popular web apps, same behaviour everywhere.

So my question is why don't they use full screen for these high resolution screens?

One reason cab be that they don't want to make everything bloated(extra large) for big screens but not all high resolution screens are big screens.Nowadays there are ultra hd monitors available.

Youtube screenshot for high resolution display

  • 1
    have you considered cognitive load? Commented May 16, 2018 at 13:25
  • 1
    As RobE mentions, we know [citation needed] that trying to read too-wide lines of text is an increased cognitive load... I don't know whether anyone's done similar tests on scanning arrays of images/film-clips, but I'd be very surprised if a similar effect isn't seen there (if your two "empty spaces" each had two more columns of videos in them, there'd be 10 per line, and I'm pretty sure I wouldn't be comfortable scanning through that.
    – TripeHound
    Commented May 18, 2018 at 9:11

4 Answers 4


No one can give you a 100% accurate answer to this question. I personally think because the percentage of users worldwide that use a resolution that big is not big enough to put resources into optimizing for those resolutions.

That being said, i am browsing YouTube on an 27 iMac with Retina Screen (5120 x 2880px) and i don't mind those white spaces. I don't feel like i have a worse experience then at home (where i browse on 1920x1080px).


One reason could be the necessary testing/QA resource - whatever team/company is building the app maybe doesn't have enough to make sure it all works as expected. To be fair, this seems unlikely at youtube!

The other reason could just be limited initial specifications. Much like how specs typically include OS/browser targets, they also usually include resolution targets.

In general, the likelihood is that more effort goes to making sure content works at lower resolutions (for mobile devices), due to the common direction towards a mobile-first approach and the potentially larger user base, rather than higher resolutions.


From my personal experience, I like to put content into container wrapper, that has max-width. Seriously, you need to take care for Desktop, Tablet, Mobile Landscape and Mobile Portrait viewports at the time developing a design. Add and XL-desktop to the mix and you basically multiplied your design requirements/worries.

From user perspective - users have very limited focus and brain capacity - add bigger canvas and you confuse them instantly, losing their interest and dropping conversion rates instantly.

However, more and more websites are using this body space for advertising and add clickable ads to sides. I hate it.


It a matter of justifying the additional effort of supporting screens that big with so few users. Design, development, testing, support, etc.

Here are some stats on higher resolution displays, your imac isn't on there so its less than 1%, probably quite a bit less. https://www.w3schools.com/browsers/browsers_resolution_higher.asp

Also with a screen that big, not everyone uses it full screen so the percentage of users would be smaller than just the % of screens with high resolutions.

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