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18 August 2021

What is 4K TV?

With four times the detail of high-definition telly, 4K Ultra HD is starting to become more widely available. But is it worth buying a 4K TV?
Martin Pratt

The number of 4K movies and shows you can watch in ultra-high definition is always increasing and if you're in the market for a new TV it should definitely be a 4K set.

You'll also see names like Ultra HD, UHD and even 4K Ultra HD being bandied about - but they all refer to the same thing. This is a TV with a resolution of 3,840 x 2,160 pixels, more than 8m pixels in total, which is four times the number in Full HD (1,920 x 1,080).

What's so special about 4K TV?

Watching 4K you'll see everything on screen in crystal-clear clarity and sumptuous detail. There's a level of detail and depth that HD sets simply cannot achieve – at times, it almost feels 3D.

All the big brands, including Samsung, Panasonic, LG and Sony, now have large ranges of 4K TVs, from entry-level models to monster sets costing many thousands of pounds.

You'll generally find that 4K TVs are big-screen models of 40 inches or more. This is because to really appreciate the higher picture quality you need to watch it on a large TV, as it's rather lost on a small screen.

how does 4k compare graphic

Where can I find 4K content?

Our highest rated 4K TVs are outstanding, and you’ll be getting a great TV if you buy one. However, bear in mind that just as with HD in its early days, we’re still a way off settling down to our evening's viewing in 4K quality.

There are some big challenges ahead before 4K is a staple of most households’ TV watching. But content is becoming more widely available, be it through broadcast TV, ultra-HD Blu-rays and internet streaming:

  • 4K TV channels Some 4K TV channels are becoming available to watch on pay-TV services, such as BT and Sky, but there aren't many. Big technical challenges remain in introducing 4K channels on to subscription-free service Freeview, and we feel this will be a big factor in this technology going mainstream.
  • Blu-ray More and more 4K ultra-HD Blu-rays arrive on shelves every month, but you’ll pay a premium, not only for the discs but for the players as well. 4K Blu-ray players start at around £180 – check out our Blu-ray DVD player reviews to find the one for you.
  • 4K internet video streaming Content providers such as Netflix, Amazon Video and YouTube have already begun streaming content in 4K. But you'll need at least 15Mpbs broadband (ideally 20Mbps or higher) to get a reliable stream. Before more 4K channels become available, internet streaming will likely be your biggest source of 4K content.
  • Catch up services It may be some time before we see BBC One 4K or ITV 4K, but adding 4K content to iPlayer or ITV Hub is closer than you think, in fact it has already begun. The BBC is trialling 4K HDR content on its catch-up service, most recently with the World Cup and Wimbledon.

Should I buy a 4K TV?

Since most of TVs released by the big manufacturers are 4K, they tend to make up the bulk of the top rated sets our lab uncovers, while Full HD is typically only available only on their cheaper sets. Plus, 4K TV prices continue to drop, so if you’re looking for a new TV, we’d recommend buying one with a 4K display.

But with HD still forming the bulk of content available to watch, if you’ve got an HD TV that you’re happy with, you shouldn’t feel the need to rush into replacing it.

That said, our testing has found that 4K sets are better than at displaying HD content than Full HD sets. The graph below shows that no matter the size of the TV, 4K sets have the edge in terms HD picture quality.

Average HD picture quality graphic

New technology is emerging that can compress the huge amount of data involved in 4K into forms that are easier to distribute not just on television, but also on Blu-ray discs and over the internet.

Although it took HD TV more than a decade to become a mainstream after the first HD TVs launched in 1998, we don't think it will take so long for 4K ultra HD. You certainly won't be wasting your money by going for a 4K TV, but just bear in mind that you won't swimming in 4K content just yet.