What is 4K - Ultra HD?

Danny Rawles
Yellow 4K logo

4K, Ultra High Definition or UHD is the next generation successor to HD.

With 4 times the detail of HD, 4K video is truly stunning.

If you're starting to feel like HD pictures just aren't good enough, then you've come to the right place because with 4 times the detail of HD, 4K will blow your socks off.

Full HD has a resolution of 1920x1080 which to be honest is still fantastic, especially when you compare it to standard definition TV, DVD or low quality YouTube videos.

But of course there's always room for improvement and the technology world doesn't sit still for long. And let's face it, TV manufacturers and movie studios always need something new to sell to us.

4K content is truly mesmerising. The picture is so sharp, immensely detailed and vivid it almost gives the impression of being 3D because everything looks so real.

I definitely recommend checking out 4K for yourself if you get the chance. The only problem is, you'll be left wanting more and wishing all your TV viewing could be in 4K.

4K Resolution

4K offers a resolution of 3840x2160. A quick bit of maths reveals this is twice the horizontal and vertical resolution of Full HD which means 4K has 4 times the amount of pixels (or detail) overall.

That's a pretty huge increase in detail considering a modern Blu-ray film played back on a top-end HDTV can still look mightily impressive.

To slightly confuse matters though, the true resolution of 4K is actually 4096x2160 and this is where the name 4K comes from.

'K' meaning 1,000 - so 4K is another way of saying 4,000.

This resolution was defined by the Digital Cinema Initiatives and is what the film industry refer to as 4K, however for consumer technology 4K/Ultra HD is defined as having a resolution of 3840x2160.

What is Quad HD?

There is also Quad HD which shouldn't be confused with 4K. Although the name suggests 4 times the number of pixels, it's actually 4 times the HD Ready resolution not Full HD.

Quad HD resolution is 2560x1440 and is starting to appear on some new premium smartphones such as the Samsung Galaxy S6 and the Google Nexus 6.



Aspect Ratio


HD Ready (720p)

1280 x 720



Full HD (1080p)




Quad HD




4K / UHD




Should I buy a 4K TV?

A year or two ago, without hesitation I would have said no. Like most new technology, the early models were just too expensive and more importantly there was almost nothing to take advantage of that monster resolution.

Now however I would say yes especially if you're in the market for a new TV anyway.

Prices have come down considerably to the point where they don't cost a huge amount more than an equivalent HDTV. So it makes sense to future proof yourself now.

The 49" LG 49UB820V LED Smart 4K Ultra HDTV
The 49" LG 49UB820V LED Smart 4K Ultra HDTV - Available for just £699

For example you can buy the fabulous 49" LG 49UB820V LED Smart 4K Ultra HDTV for only £699

That's incredible value considering not long ago you would have only got a mid-range 40" HDTV for that price.

The world's first consumer 4K TV came courtesy of Sony. The XBR-84X900 launched towards the end of 2012 and would have cost you an eye watering £25,000.

In order to help try and shift a few units, Sony even included a "free" 4K Ultra HD Video Player containing ten 4K movies from Sony Pictures.

4K content

Native 4K content is really something to behold. If you're still not convinced just pop along to your nearest TV store to see for yourself. The only slight problem is there's not much native 4K content out there.

This is steadily improving though with streaming services such as Netflix and Amazon Prime Instant Video now offering some content in 4K resolution. You will have to pay slightly more on Netflix, however Amazon Prime's 4K content is automatically included in the price.

There are also rumours that Sky are working on a 4K channel (of course they are) but overall, content wise it's still fairly slim pickings.

4K Blu-ray?

4K Blu-ray or Ultra HD Blu-ray as it will be officially known is finally coming and on target for the end of the year. This will no doubt be the game changer for 4K and the killer app that's sorely missing.

Blu-ray discs don't currently have enough capacity to hold a full length feature film in 4K. The capacity of standard Blu-ray discs is 25GB (single-layer) and 50GB (dual-layer).

The new Ultra HD Blu-ray discs will have a capacity of 66GB (dual-layer) and 100GB (triple-layer).

4K upscaling

Finally there is 4K upscaling. This is where either the TV or a Blu-ray player takes an SD or HD video and scales it up to fill the full 4K resolution.

The quality of the upscaled video largely depends on how good the scaler is. An upscaled video will never look as good as native 4K content but it's the next best thing.

The latest Blu-ray players such the superb Sony BDPS7200 ensure the picture quality is as good as it can possibly be whether you are watching DVDs, Blu-rays or streaming content.

So that's it then, the future is 4K?

Well not quite - did I mention that 8K is already nipping at 4K's heels!...

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