If you’ve bought a modern TV lately, chances are most of the connections are HDMI 2.1. This high-speed cable is one of the best ways to connect your soundbar, games console, home theater system, and UHD Blu-ray player to your TV. It has full support for the latest 4K and 120Hz standards, supports eARC, and is entirely backward compatible with older generations of HDMI.
In short, HDMI 2.1 is the only connector you need for pretty much any modern device that connects to your TV. You don’t have to use it for older devices, but unless you’re sitting on a stack of older HDMI cables, you might as well.
What is HDMI 2.1?
HDMI 2.1 is the latest generation of HDMI cable and connection technology, offering higher bandwidth, greater support for higher resolutions and refresh rates, and support for new features. Where previous generations made incremental improvements to the standard, HDMI 2.1 made a major leap, turning it into the premier connection standard for consumer devices in the living room.
Supported by the latest games consoles, graphics cards, TVs, monitors, and Blu-ray players, HDMI 2.1 is the best way to connect most modern media devices together. Although DisplayPort 2.1 does offer greater bandwidth, that’s more of a desktop PC connector type.
HDMI 2.1 supports all the traditional audio and visual technologies, too, including Dolby Atmos and DTS:X multichannel surround sound, HDR metadata, and all the other little bits that need to get from a 4K Ultra HD Blu-ray player or a streaming media player to a TV. It also adds support for variable refresh rates, quick media switch, auto-low-latency mode for gaming, and source-based tone mapping, among other features.
The really big change with HDMI 2.1, though, is the added bandwidth. With up to 48 Gbps of total throughput, it’s close to three times as capable as HDMI 2.0. That gives it support for 4K resolution at up to 144Hz on gaming PCs, or up to 120Hz on consoles. It also supports 8K resolution at up to 60Hz, and up to 10K resolution for professional billboards and other displays.
What can HDMI 2.1 do that HDMI 2.0b can’t? What’s new?
Resolution
As we’ve established, HDMI 2.1 allows for higher resolutions at higher frame rates than before. With HDMI 2.0b, we could enjoy a maximum of 4K resolution at a maximum frame rate of 60Hz. With HDMI 2.1, we can get 4K at 120Hz, 8K at 60Hz, and up to 10K resolution for industrial and commercial applications.
This is particularly great news for gamers, as higher frame rates mean smoother, better-looking games. It’s also great news for the film industry, and the HDMI organization says some Hollywood directors are eager to migrate to 120Hz native filming as they look to deliver high frame rate content to the big screen and beyond.
eARC
The Audio Return Channel (ARC) is an HDMI 2.0b feature that lets audio move back and forth over an HDMI cable between a TV and an AV receiver or soundbar. Unfortunately, the limited bandwidth of HDMI 2.0b means that audio is often compressed and reduced down to stereo, resulting in “lossy,” lower-quality audio.
With HDMI 2.0’s Enhanced Audio Return Channel (eARC), we can now get uncompressed, full-resolution audio over HDMI 2.1 connections. Dolby Atmos is a perfect example. With ARC, Atmos only works when using Dolby Digital Plus, a compressed audio signal. eARC lets Dolby Atmos give its best performance using Dolby TrueHD, a “lossless,” high-resolution audio signal.
This will simplify system setups dramatically because it means users can connect everything to their TV and then run a single HDMI cable to their receiver or soundbar without losing sound quality. Fewer cables, less mess, better sound!
Dynamic HDR
The high-dynamic range is already the best improvement to TV picture quality since 1080p HD, but it can be even better. If you’re at all familiar with Dolby’s version of HDR, Dolby Vision, then you likely know the reason some reviewers consider it superior to other formats — it is a “dynamic HDR” medium. In other words, Dolby Vision makes changes to the settings of an image as the image itself changes. The result is a more accurate, vibrant, and … well … dynamic picture.
The only hangup with Dolby Vision is that it is a proprietary technology, and not every electronics manufacturer wants to pay licensing fees to use it. HDMI 2.1 brings dynamic HDR performance to other flavors, including the dynamic version of HDR10, known as HDR10+, and others, which should bring better HDR experiences to more TVs and more formats.
But wait: Isn’t HDR10+ already possible using HDMI 2.0b? Technically, yes, but it’s not an officially supported technology when done over HDMI 2.0b. HDMI 2.1 makes it official, which in turn should make it highly reliable.
Variable refresh rate
As we mentioned in the section on resolution, HDMI 2.1 can support higher frame rates for smoother video. But just as importantly from a gaming perspective, it allows for variable frame rates. Modern PC and console games do not use a single frame rate throughout the game. It varies — sometimes by quite a lot — depending on the complexity of the scene.
When frame rates drop or speed up, there is a mismatch between what the game is providing and what the TV is set to display. To compensate, the TV has to do some guesswork, and the result isn’t pretty. Lag, judder, and frame tearing are all symptoms of trying to play VRR games on an HDMI 2.0b non-VRR-capable display. HDMI 2.1 gives TVs the ability to be perfect big-screen gaming companions. That’s especially important if you are using new consoles like the Xbox Series X or PS5, which are built with VRR in mind.
Quick frame transport
This feature reduces the time it takes for a frame of video to pass from the source device (like a PC or console) to a display (like a TV or virtual reality — VR — headset). Again, this is great for gamers, who will notice much less lag, especially those who like fast-action, first-person shooters. VR users will benefit from an equally reduced time between movements and the world presented through their goggles.
Quick media switching
Utilizing the same HDMI VRR mechanism that hardcore gamers have been taking advantage of, Quick Media Switching (QMS) is a cool HDMI 2.1b feature that eliminates something called “blackouts.” This is that one- to three-second dropout in signal that occurs when you’re switching from one HDMI source to another. As long as Source B has the same resolution as Source A, HDMI 2.1b should allow you to change inputs without any blackout time whatsoever.
Auto low-latency mode (ALLM)
Yet another improvement for gamers, ALLM lets a TV or other display know when the signal is coming from a game console or PC. When that happens, the display can automatically turn off any picture processing that could introduce latency or lag. You’ll never have to select Game Mode on your TV again.
No more lip-sync issues
With older HDMI standards, it could be a hassle to sync the video from your TV with the audio from your receiver or soundbar. This is because the TV may be using a heavy amount of processing, while the audio system’s processing takes far less time than the video processing.
The result is a delayed output of a video signal relative to an audio signal, and the result of that mismatch is sound that (oh-so-frustratingly) doesn’t match the timing of your picture. HDMI 2.1 makes it possible for TVs to talk in real time to AV receivers, soundbars, Blu-ray players, game consoles, and other source devices to ensure your video and audio are in perfect sync all the time.
What’s the difference between HDMI 2.1a and 2.1b?
HDMI 2.1b is the latest HDMI 2.1 standard, and it introduced a few new features. As per the official specifications, HDMI 2.1b introduces official support for 10K resolution, and better support for dynamic HDR and source-based tone mapping. You don’t need to upgrade your cables to enjoy these features, though, with software updates doing all the heavy lifting.
Do I need to use HDMI 2.1?
Absolutely not. If your TV supports 4K UHD resolution and high-dynamic-range (HDR), you can stream 4K movies just the same. Similarly, if you’re watching 1080p Blu-rays, or are happy to play older console games, or limit yourself to a maximum of 60Hz at 4K resolution, then older HDMI cables and connectors are perfectly viable.
HDMI 2.1 just gives you more options. It lets you play Xbox Series X/S and PlayStation 5 games at up to 4K resolution at a 120Hz refresh rate. It supports 8K resolution if you want to connect your PC to a high-end monitor or TV. It supports dynamic HDR and source-based tone mapping, among other features. You won’t get those with an older HDMI 2.0 cable, for example.
Is it OK to buy a TV that doesn’t have HDMI 2.1?
Sure, if you aren’t going to use its features. But that goes for most TV features. All flagship TVs from the top manufacturers come with HDMI 2.1 support, and even most mid-range and entry-level TVs will have one or two. Budget TVs sometimes don’t, so take that into consideration if it’s a feature you want to buy.
Want additional pointers on buying a new TV? Check our our TV buyer’s guide.
If you’re currently in the market for a high-end TV, better to go with an HDMI 2.1-capable model that won’t break the bank and future-proof your home theater setup. On the other hand, if you’re more interested in saving money and looking for deals, don’t be afraid to pick a TV with HDMI 2.0, as long as you understand what you’re giving up.
Does HDMI 2.1 require new HDMI cables to work properly?
Yes. Since the new standard nearly triples the amount of data that can fit down an HDMI cable at once, a new cables is necessary. Although it’s backwards compatible with older HDMI standards, to take full advantage of HDMI 2.1, you’ll need to use a new Ultra High-Speed Certified HDMI cable.
In some rare instances, it may be possible to use an existing Certified High-Speed HDMI cable with a newer HDMI 2.1 device, but since the amount of information being crammed down this digital pipeline is increasing at a rapid rate, we advise you to buy new Ultra High-Speed HDMI cables along with any HDMI 2.1-capable device that doesn’t already include them. If that sounds expensive, don’t worry — they don’t cost much more than standard High-Speed HDMI cables.
Wondering which HDMI cables you should buy? Check out our list of recommended HDMI cables for all kinds of devices and installations. Focus on the speed certifications of your cable, which helps ensure you’re getting a cable that is capable of supporting important HDMI 2.1 features.
It’s easiest to do this in person if possible: Look for the holographic. Ultra Certified Cable label attached directly to your HDMI cable, which includes a little QR code for authenticating. This stands for certification by the HDMI Licensing Administrator, so you know the cable can handle the speeds necessary to enable many important HDMI 2.1 features, such as high resolutions paired with higher refresh rates.
Is HDMI 2.1 backward compatible?
Yes. You will be able to connect any HDMI-enabled device supporting any older version of the HDMI standard, and it will work just fine on a new HDMI 2.1-enabled TV or display. Ultra High Speed HDMI cables are backward-compatible too. For instance, if in the future you want to connect your then-archaic Xbox One to your shiny new 8K TV with HDMI 2.1, that won’t be a problem at all. Nothing is changing about the size or connection type of the HDMI cable ports and jacks.
Can my HDMI 2.0b devices be firmware upgraded to HDMI 2.1?
No. While there are premium chips out there that can be firmware upgraded, they are extremely expensive and rarely used by manufacturers. Chances are that your existing HDMI 2.0b devices don’t have one of those rare chipsets built into them.
Do monitors have HDMI 2.1 too?
Yes, they do — there are some excellent monitors with HDMI 2.1, especially for gaming. And brands like Asus have whole pages devoted to it. Keep in mind that you’ll need a GPU that also supports HDMI 2.1 features to really benefit, but most modern graphics cards have that. You don’t absolutely need HDMI 2.1 to reach 120Hz or even 144Hz refresh rates, but it is important for supporting both high refresh rates and high resolution at the same time.
Are there downsides to switching to HDMI 2.1?
If you were waiting for the catch in all of this coolness, there’s a potentially significant one. Unfortunately, that “HDMI 2.1” sticker on your TV’s box doesn’t guarantee that the display in question actually supports the all the HDMI 2.1 features that matter to you.
For instance, several of Sony’s 2021 HDMI 2.1 TVs shipped without VRR, though a batch of firmware updates released the following year began adding the capability to select TVs. Toshiba’s C350 Series Fire TV has a single HDMI 2.1 port, which supports eARC and will get ALLM with an update, but the TV will never do VRR or 4k at 120Hz. And while QFT (Quick Frame Transport for low latency) is available on cables
If you feel yourself hurtling back to square one, don’t panic. When shopping for a new HDMI 2.1-capable TV, just make sure to do your due diligence and see which of the HDMI 2.1 features the TV/manufacturer supports. Bottom line: Not all HDMI 2.1 TVs are created equal, so buyer beware!
Special thanks to Jeff Park at HDMI LA, Brad Bramy at HDMI.org, and Chris Heinonen of Wirecutter and Reference Home Theater for providing deep technical background for this article.
