HDMI 2.1: What you need to know for gaming, 8K TVs and more in 2021 – CNET

HDMI 2.1 is here. It’s available now on many 2020 and 2021 TVs, including models from LG, Samsung, Sony and others. It’s also on both of the next-generation game consoles, the PlayStation 5 and Xbox Series X. To get the most out of those consoles you’ll need a TV that supports at least some features of HDMI 2.1.

That doesn’t mean you should go out and buy a new TV right now, or even that your next TV needs HDMI 2.1 capability. Those new game consoles will play perfectly well, and still look spectacular, on a TV that lacks HDMI 2.1. Many midrange and higher-end sets support the new connectivity standard, however, so if you’re in the market for a new TV, it’s worthwhile to understand what it means.

The short version is HDMI 2.1 brings new features and a lot more bandwidth. That means higher resolutions, higher frame rates and more. The connector itself isn’t changing, however, so your new HDMI 2.1 gear will be backwards compatible with your current cables and equipment, though if you want to take advantage of everything 2.1 has to offer, you’ll need some select upgrades. Here’s what you need to know.

Read more: Best HDMI cables for your new 4K and HDR TV

The really short version

Don’t like reading (much)? Allow me to fire some HDMI 2.1 bullets.

• The physical connectors and cables look the same as today’s HDMI.
• Improved bandwidth from 18 gigabits per second (HDMI 2.0) to 48Gbps (HDMI 2.1).
• Can carry resolutions up to 10K, frame rates up to 120 frames per second.
• New cables are required for higher resolutions and/or frame rates.
• Many new TVs have at least one HDMI 2.1 input.
• The main sources that can take advantage of 2.1 right now are the PlayStation 5 and Xbox Series X, as well as high-end graphics cards like the Nvidia GeForce RTX 3090 and RTX 3080.

The increased resolution and frame rate possibilities are a futurist’s dream:

• 4K50/60
• 4K100/120
• 5K50/60
• 5K100/120
• 8K50/60
• 8K100/120
• 10K50/60
• 10K100/120

You should be able to get 4K/60, and a basic 8K/30, with current cables, but the rest will need an Ultra High Speed HDMI cable. More on these new cables below.

On the color front, 2.1 supports BT.2020 and 16 bits per color. This is the same as HDMI 2.0a/b, and is what makes wide color gamut possible.

Those are just the highlights, though. Read on for the details.

All about the bandwidth

When you increase the resolution of a TV signal, the amount of data of that signal goes up. A 3,820×2,160-pixel 4K Ultra HD signal sent over HDMI is roughly four times the amount of data as an HD 1,920×1,080 signal. If you think of cables as pipes, you need a bigger pipe to transmit a 4K signal than a 1080p one. The same is true if you increase the frame rate. You need a bigger pipe to transmit a 60fps image than you do a 24fps image of the same resolution. More images per second means more data.

Though most current HDMI cables can handle nearly all of today’s content, the TV industry never sits still. We’re already seeing TVs that are capable of higher frame rates, when sent such content, plus higher resolution TVs, like those with 8K. Don’t worry, they’re not going to be common any time soon. Even way farther down the road, maybe we’ll see 10K TVs.

This is predominantly what HDMI 2.1 is for: higher resolutions and frame rates that aren’t necessary for most people right now.

Unless you’re a gamer. PCs, and high-end gaming rigs at that, plus the PS5 and Xbox Series X are the only current sources that can output 4K at more than 60fps. While there are a handful of movies or TV shows with higher frame rates, you won’t find those versions on Netflix or Vudu. 

While we are seeing a handful of 8K TVs, actual 8K content is almost nonexistent. This is largely because 8K sources are basically nonexistent. Your average Roku or Apple TV can do 4K and that’s it. 

So as far as the additional potential bandwidth of HDMI 2.1, when it comes to resolution and frame rates, only a few TVs can take any advantage of it, and then only with gaming consoles and PCs. There’s more to HDMI 2.1 than just bandwidth, however.

New features

While the new resolutions and frame rates get all the headline buzz, but there are some other improvements that will be more useful for most people.

Dynamic HDR is an amusing name for a big improvement. High dynamic range is our favorite picture-quality improvement since high-definition itself, and right now the most common HDR format is HDR10. It uses something called metadata to tell the TV how to treat a piece of HDR content. In the current version of HDR10, that metadata is applied once and once only, on a per-program basis. As in, you get One Set of Data to Rule Them All.

Dynamic HDR can vary how each scene or even each frame looks, not just the program as a whole, to better suit that scene (or frame). Here’s a video that shows some examples (but remember, you’re viewing it on non-HDR screens). Basically, a dark scene with bright highlights (campfire at night) would take advantage of HDR differently than a bright scene with dark areas (someone under a pier on a beach at noon). If these scenes were in one movie, static HDR would treat these the same, while Dynamic HDR would let each scene look its best. HDMI 2.1 enables Dynamic HDR, but it also needs to be present in the content to work. 

Dolby Vision and HDR10+ already use dynamic metadata and can pass over a existing HDMI connections. This aspect of HDMI 2.1 ensures going forward this will be possible without a proprietary format (HDR10 has no licensing fees). 

eARC is the next evolution of Audio Return Channel, which allows simpler connections between AV devices like TVs, video players and sound systems. eARC has support for “the most advanced audio formats such as object-based audio, and enables advanced audio signal control capabilities including device auto-detect.”

Basically this means Dolby Atmos over ARC at full resolution, which you currently can’t do. However, your current cables probably can. If, in the future, you buy an HDMI 2.1-compatible TV and an HDMI 2.1-compatible sound bar, your current High Speed cables should be able to transmit eARC. Audio doesn’t require the bandwidth that video does.

Game Mode VRR is a potentially interesting feature for gamers. It allows for “variable refresh rate, which enables a 3D graphics processor to display the image at the moment it is rendered for more fluid and better detailed gameplay, and for reducing or eliminating lag, stutter and frame tearing.” In other words, there will be less of a buffer for frames while the video card creates the image so you won’t have to choose between image artifacts and input lag, ideally reducing both. If this sounds familiar, it’s because it’s similar to Nvidia’s G-Sync and AMD’s FreeSync, both only available over DisplayPort. We wrote more about this feature in How HDMI 2.1 makes big-screen 4K PC gaming even more awesome.

Game Mode VRR will also work over current cables (between two pieces of 2.1-compatible gear), though if you’re trying to push greater-than-4K60 video, you’ll need an Ultra High Speed HDMI cable. 

Speaking of which…

New cable

For the first time in a while, there is a new cable. It looks… well, it looks the same as the old cable. There’s no new connector; that stays the same. These were originally called “48G” cables since they will have 48Gbps bandwidth, though now they’re officially called Ultra High Speed HDMI cables. These have roughly 2.6 times the 18Gbps bandwidth that the better-made HDMI cables have now. These cables are backward compatible, so they’ll work with all your other HDMI gear (at whatever speed that gear operates).

You probably don’t need to buy Ultra High Speed HDMI cables cable right now. Even with 4K TVs nearly all your gear should work fine with your current cables. There are, however, important exceptions. The biggest is with the new gaming consoles, the PlayStation 5 and the Xbox Series X. These are capable of 4K resolutions at 120 frames per second. That’s almost certainly going to require a new cable. We’ll talk more about those consoles below, but the short version is, if you want 4K120 and you have a new TV that can handle that resolution (older TVs almost universally can’t), check out Ultra High Speed HDMI cables.

PlayStation 5 and Xbox Series X

You can connect the PS5 and Xbox Series X to any TV you could connect a PS4 and Xbox One X to. You don’t need a new TV. You probably don’t need new cables either. Definitely not if you have a 1080p TV. If you have a 4K TV and want to play these new consoles in 4K, your current cables will probably work. You’ll know pretty quickly: If you connect the console and the TV says it’s a 4K signal, you’re good to go. 

There are, however, exceptions that relate to HDMI 2.1. Both new consoles are capable of 4K up to 120 frames per second. Some new TVs can handle this higher frame rate. Almost no older TVs can, even those called “120Hz.” The TV will need HDMI 2.1 to let the console run in all this high frame-rate glory. Your current HDMI cables probably won’t be able to handle 4K120. You’ll need Ultra High Speed HDMI cables, which thankfully, aren’t that much more than “regular” HDMI cables at this point. 

One final important reminder: if you have a receiver or soundbar in your system, and the game console is connected to that, it too has to be HDMI 2.1 in order to pass 4K120. A chain is only as strong as its weakest link, so to speak. So if your console is 2.1, your TV is 2.1, but your receiver is 2.0, you’ll only get resolutions and features possible with HDMI 2.0. 

Do you need to upgrade?

Probably not. At least, not yet. Right now the only common source that can really take advantage of what 2.1 has to offer are the PS5 or Xbox Series X. If you really need 4K120 in your gaming life, then it’s worth looking for a TV that can take advantage of that.

If you’re buying an 8K TV for some reason, it’s worth considering getting Ultra High Speed HDMI cables too. Not because there’s anything that requires that bandwidth now, the consoles notwithstanding, but it can’t hurt for a bit of future-proofing. 

One last thing to keep in mind: Not all TVs that claim HDMI 2.1 compatibility are actually capable of everything we’ve discussed. In fact, most aren’t. A TV with a 4K120 input might also have eARC, but not necessarily on the same input. A TV might have eARC, but not have any high frame rate or high resolution inputs. It’s confusing, to say the least. Best to do your homework on what models can do what before you get your heart set on something specific. In some cases manufacturers can add 2.1 features to already-sold TVs, but don’t count on this. It’s fairly rare and in some cases not possible because of hardware limitations.

HDMI 2.1 is like a brand-new 10-lane highway in the middle of the countryside. It’s only useful for a few specific reasons, but it offers an easy way to expand in the future. The villages at each end of that highway are rapidly getting bigger. Fortunately, more and more TVs are shipping with HDMI 2.1, so with any luck your next TV will have it regardless. Then you’ll just (maybe) need to worry about cables.

As well as covering TV and other display tech, Geoff does photo tours of cool museums and locations around the world, including nuclear submarines, massive aircraft carriers, medieval castles, airplane graveyards and more. 

You can follow his exploits on Instagram and YouTube, and on his travel blog, BaldNomad. He also wrote a bestselling sci-fi novel about city-sized submarines, along with a sequel.