High definition has meant 1080p (1,920 by 1,080) resolution for years now, and it's ready for an upgrade. That's where ultra high-definition, or UHD, television comes in. You might have heard it called 4K. It's technically UHD according to the now-Consumer Technology Association, but the two terms have become interchangeable. And now those terms finally matter a lot to your television buying decisions, since 4K is finally a mature, accessible technology.
What Is 4K?
A UHD or 4K display is one with at least 8 million active pixels. For televisions, that resolution has standardized to 3,840 by 2,160. Digital cinema 4K (the resolution in 4K movie theaters) is slightly higher at 4,096 by 2,160. However you define it, it's four times the number of pixels on a 1080p display, and over 23 times the resolution of standard definition television.
For starters, 4K is obviously much sharper than 1080p. In the space that a 1080p TV holds a pixel, a 4K TV of the same size can hold four. That makes for a significant jump in clarity, assuming you have native 4K source material to watch in that resolution.
Because the resolution is much higher, it requires more bandwidth to transmit. The HDMI 2.0 standard was developed to support 4K, and allows 2160p video to be displayed at 60 frames per second. Older HDMI standards could work with a 4K source to some extent, but not reliably or at that framerate. You can also stream 4K video over the Internet, which similarly requires a very fast connection; Netflix recommends a steady 25Mbps downstream speed to watch 4K content over its service.
If you don't have a 4K source video, a 4K TV can still make your movies and shows look better. All 4K televisions use some kind of upconverter to display 1080p and lower resolution video. These upconverters do more than just break each pixel into four identical pixels; they employ edge smoothing and noise reduction algorithms to produce, ideally, a sharper picture. When it works well, you get video that looks natural on a 4K screen (though it doesn't add any actual new details, just sharper lines and more even color and light). When it doesn't, the picture can look a bit blotchy, like a painting.
While some regular viewers struggle to see the difference between 1080p and 720p in smaller television sizes, it's much more obvious on 50-inch and larger TVs. 4K is another significant jump in terms of clarity and detail, especially as people are becoming more and more used to the incredibly tiny pixels displayed by today's Retina-style HD screens on mobile gadgets. This is a major factor for large TVs as well, since 55 inches has become a low boundary for just how big a big screen can get.
What About HDR?
High dynamic range (HDR) is a video format available on some high-end new TVs. HDR content has the same resolution as regular 4K video, but each pixel can be assigned a much wider and more granular range of color and light. This lets HDR video appear significantly more detailed, accurate, and lifelike than standard dynamic range video. However, you need an HDR-compatible display, and the content needs to be encoded in an HDR format like HDR10 or Dolby Vision. If you don't have an HDR television, don't worry; all physical media and streaming services that offer HDR content can display SDR versions of the same material on screens that don't support the format.
What 4K TVs Are Out There Now?
4K TVs have been hitting the market for a few years now, and have finally become both affordable and functional. 4K no longer has the pricing premium of early adoption, and you can get a good-performing 4K television for about the same price as a mid-to-high-end 1080p TV last year.
Vizio's Du and LG's UH8500 series both stand out with surprisingly good picture quality for reasonable prices, and if you want to save even more (and are willing to compromise on picture quality), TCL's UP130 series of 4K Roku TVs are even less expensive. You can still go all-out if you want a flagship TV and are willing to spend big bucks; LG's OLED65B6P and OLED65G6P 4K OLED televisions are, quite simply, the most impressive displays we've ever tested, but they're also much pricier than similar sized LCD TVs.
The availability of such a broad range of 4K TVs indicates that the market has matured past the point of early adopters and technophiles, to suit a wide range of buyers looking for the best new tech.
What 4K Content You Can Watch?
Thanks to Amazon and Netflix, there's a surprising amount of 4K content you can watch if you have a fast-enough Internet connection. 4K has gone past the eye candy landscapes and tech demo phase that early HD content went through, and now you can find plenty of television and movies in the format, like Breaking Bad, Jessica Jones, and Luke Cage. Both services are steadily adding more 4K content, and if that isn't enough, YouTube supports 4K video for anyone from studios to GoPro users. Many of our favorite media streamers have options for ultra high-definition content as well.
Besides streaming, you can actually buy 4K movies on physical media now. Ultra HD Blu-ray discs have begun trickling into stores, and major studio releases are increasingly coming out on this new format. It is a very new format, though, so you'll need a new player. Ultra HD Blu-ray players are still very rare and pretty expensive; the Samsung UBD-K8500 we reviewed costs a few times as much as a regular Blu-ray player, while the Microsoft Xbox One S offers both disc playback and all the features and games you get from a full, modern video game console. If you prefer to wait for the players to become more affordable but would like to build your 4K media library now, many Ultra HD Blu-ray releases are Ultra HD + Blu-ray combo packs, which include both the Ultra HD and standard Blu-ray discs (and often Ultraviolet codes for a digital copy).
Bottom Line: Do You Need 4K?
You probably don't need 4K quite yet, but this might be the year to get one anyway. At least, if you're looking to replace your television because it's outdated or broken rather than simply not new enough, it's a good time to look for a 4K model. The tech has become standardized enough that you can be reasonably sure a 4K television you purchase now will be ready for the future (just make sure it has HDMI 2.0 ports), and it's affordable enough to be compared directly with 1080p televisions in price.
For more, check out our TV Product Guide and our list of The 10 Best TVs.