What Is 4K (Ultra HD)? (2024)

We're well into the age of 4K now. HDTVs with 1,920-by-1,080 resolutions have been effectively placed with bigger, brighter 4KTVswith four times as many pixels. 4K has gone through its early steps and various growing pains for early adopters, and is now solidly mainstream as the standard type of TV you can buy. You can find 4K TVs in all sizes and prices, including 65-inch models for well under $1,000. If you haven't made the jump to 4K yet, this is a good time to do it. Here's what you need to know.

What Is 4K?

A 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.

This means 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. Even if you don't, companies like LG, Samsung, and Sony have developed impressive upconverting technologies that scale 1080p and lower resolution content to 4K with various image enhancements. It isn't as good as native 4K content because you can't simply synthesize additional detail out of nothing, but it's a good backup.

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. This was initially a concern as HDMI 2.0 was becoming more commonplace, but right now you can count on nearly any home entertainment device you buy to support HDMI 2.0, andbased on our testsyou'd have to really go junk shopping to find an HDMI cable that can't transmit a 4K60 HDR picture. You can also stream 4K video over the internet, which similarly requires a fast connection; Netflix recommends a steady 25Mbps downstream speed to watch 4K content over its service.

While regular viewers struggled to see the difference between 1080p and 720p on smaller televisions, it's much more obvious on 40-inch and larger TVs. 4K is another big jump in terms of clarity and detail, especially as people are becoming more and more used to the incredibly tiny pixels displayed by the high-resolution screens on their phones. This is a major factor for large TVs as well, especially since 65-inch models are as affordable as 55-inch TVs were just a few years ago, and even 75-inch TVs can be found for reasonable prices (with some models pushing past 80 inches, but at that point the the prices jump much higher).

Isn't 8K Coming Soon?

The short answer is no. The long answer is that 8K is already here for some high-end TVs, but it isn't going to be a major factor for some time. We go into detail about what 8K means and when you can expect it in our 8K explainer, but for now all you need to know is that some TVs are hitting 8K resolution (7,680 by 4,320, four times the resolution of 4K), but there is no consumer content available in native 8K and there won't be any for a while. There are no standardized 8K streaming formats or physical media, though. If you spend the extra money on an 8K TV, you'll be relying entirely on the TV's upconversion process of 4K or lower resolution media, and that can't be as good as native 8K content.

What About HDR?

High dynamic range (HDR)is a confusing term, and it's easy to mix it up with 4K or assume that they're the same thing. They aren't, and our guide to HDR explains the differences in more detail. HDR is a type of content, most often in 4K, that expands the range of color and light that can be shown. HDR content stores wider and more granular values of brightness, darkness, and color levels than standard dynamic range content, which lets TVs that support HDR show pictures that are brighter, darker, and more colorful. Think of it this way: 4K determines the number of pixels in your video, while HDR determines how much light and color each pixel can display. Not all 4K content is HDR, but when it is, and your TV can handle it, it looks much better because of that wider reach of light and color.

To watch HDR content you need a TV that supports HDR, ideally with a panel that can faithfully display the full range that HDR requires. Some budget TVs can decode HDR content and display it, but their panels don't get dark enough, bright enough, or colorful enough to make much of a difference over standard dynamic range content.

Which 4K TV Should You Buy?

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 find a full range of 4K TVs to fit your budget. Our guide to thebest TVsis a good place to start. TCL and Hisense have produced some impressive TVs with reasonable price tags, and on the higher end LG, Sony, and Vizio's OLED TVs pack fantastic contrast into incredibly slim designs.

What 4K Content You Can Watch?

If you have a fast enough internet connection, you can stream 4K HDR video content from most majorvideo streaming services. Amazon, Google Play, iTunes, Netflix, and Vudu all offer a wide variety of 4K movies and shows. If that isn't enough, YouTube supports 4K video for anyone from studios to GoPro users. Many of our favoritemedia streamershave options for ultra high-definition content as well.

Besides streaming, you can actually buy 4K movies on physical media. Ultra HD Blu-ray discs offer 4K HDR video on an optical disc, but you'll need a new player to play them. Ultra HD Blu-ray players are still rare and expensive compared with a standard Blu-ray player, but thePlayStation 5, Xbox Series X, Xbox One S, and Xbox One X, are all also capable of playing Ultra HD Blu-ray discs, and the will also support the format. Many Ultra HD Blu-ray releases are Ultra HD + Blu-ray combo packs, which include both the Ultra HD and standard Blu-ray discs.

On the gaming side, the PS5, PS4 Pro, Xbox One X, and Xbox Series X all offer 4K gaming to varying degrees, with the newest systems (PS5 and XSX) able to consistently push 4K resolutions for most games. If you have a good gaming PC, you should also be able to play games in 4K resolution on it, as well.

Bottom Line: Do You Need 4K?

If you're looking to get a new TV and haven't made the jump to 4K yet, now is the time. All of our top TV picks are 4K models that support HDR. The tech has become standardized to the point that you can be reasonably sure a 4K television you purchase now will be ready for the future, and it's affordable enough to be compared directly with 1080p televisions in price. Whatever your budget, you can probably find a 4K TV, very likely an HDR-compatible one, that fits your needs.

And once you find the right TV for you, make sure to read our guide on how to properly calibrate it.