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What is 4k (Ultra-HD)? All you need to know about UHD resolutions

What is 4k (Ultra-HD)? All you need to know about UHD resolutions

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Last updated: 10 February 2022

4k and Ultra-HD are terms that are used fairly interchangeably. They both refer to crystal-clear video image quality, so crisp you’ll catch the most intricate of details: from microscopic wonders of a nature documentary to all the blemishes on a presenter’s face.  At a consumer level, for the most part they refer to the same concept, although there are a handful of minor technical differences.  

What is 4k?

In the cinema world, films are watched with a 1.85:1 aspect ratio. The standard resolution is 4096 pixels wide and 2160 pixels high – hence why it’s called 4k.

But when it comes to home TV screens, the aspect ratio is slightly smaller, at 1.78:1, or 16:9. This means fewer horizontal pixels, with a resolution of 3840 x 2160p. However, the keen-eyed of you will have noticed that the number of horizontal pixels is still very close to 4k.

So, the term 4k got adopted to refer to a pixel resolution – and therefore the image quality – of our television screens. It’s just a term for digital cinema shooting that made its way into the domestic sphere.

What is UHD?

In a nutshell, Ultra HD is the consumer name for 4k. Remember when we got excited first by HD, then Full HD display? Well, a Full HD TV has a pixel resolution of 1920 x 1080p. By comparison, as we mentioned, Ultra HD has a resolution of 3840 x 2160. Twice as wide and twice as high, that means UHD gives a clarity of image four times that of its predecessor. And that makes the total number of pixels on your screen over a whopping 8 million – so you know, it’s extremely detailed.

What is Full UHD?

Because the aim is always to be bigger and better, Full UHD has come along. This has a resolution of 7680 x 4320p, making it four times as clear as UHD itself. You might be wondering whether it’s really necessary to watch The Chase with such acute definition, and we agree you’re probably right. The features of Full UHD are only really discernible on big screens and as such it tends to only be cinemas who use this at the moment (calling it 8k).

Do I need 4k?

For a long while 4k TVs were prohibitively expensive, putting them off the cards for many people. And although they’re dropping in price, they still cost a fair amount. You can find 4k TVs at Currys.

Moreover, TV content has to be available to view in UHD, and that comes down to the equipment its shot on, as well as the broadcaster. So often TV material isn’t necessarily even available in UHD, even if you have a 4k TV. By contrast, 1080p – which we know as HD – serves its purpose well in most homes with TVs being affordable and reliable.

That being said, 4k is the way technology is heading. Streaming services like Netflix are providing more and more 4k content, so eventually UHD programmes will be the norm. 4k TVs also have OLED screens rather than LED screens, making for a much richer viewing experience.  

What do I need to watch 4k?

4k viewing doesn’t just happen at the drop of a hat. There a few things you’ll need before you get to enjoy UHD.

First, you’ll need a 4k TV, though these are available from most manufacturers. Next, you’ll need a 4k compatible set-top box as part of your TV package, as well as subscriptions to any 4k channels that aren’t included. And last, you need fast fibreoptic internet. 4k demands high speeds in order to stream, so if your connection is unreliable this could be a roadblock.

What TV shows can I watch on 4k/UHD?

Unfortunately, not every channel is available in UHD at the moment. What you can access will depend on your provider and how you watch TV, though let’s take a brief look.

  • BT: With BT, you can get add-ons for sport and movies in UHD. These may even be already included if you’ve got a comprehensive TV package anyway.
  • Sky: If you have a Sky Q box, then you’ll be able to access a heap of UHD content from the likes of Sky Sports and Sky Cinema.
  • Virgin Media: You’ll be able to stream UHD content if you’ve got a V6 set-top box in addition to your Maxit TV deal.
  • Streaming services: Netflix, YouTube and Amazon Prime Video all provide UHD content. With Netflix, you’ll need the Premium subscription but for Amazon Prime Video it’s included as standard.

Looking to free services, BBC iPlayer has a handful of shows available in UHD with particular focus on nature documentaries.


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Danny Lord

Author: Danny Lord

Danny is our Editor-in-Chief, and has been writing news and guides for comparison sites for the last five years.