HDMI explained: What you need to know and what is the best HDMI cable?

Since HDMI ports and cables first appeared in 2002, they’ve created both opportunities and challenges in AV connections.

Notably, they’ve led to rapid obsolescence in AV equipment as specifications advanced. Their inherent fragility often results in broken cables, particularly with frequent plugging and unplugging.

Different HDMI sockets on different devices have bamboozled consumers by supporting different features, leaving many unaware of specific bandwidth or feature limitations. Long HDMI cable runs often produce no picture or reduced quality due to signal loss over distance.

Last but not least, ever increasing data demands placed on HDMI cables means they now come in a number of different grades that you actually need to have at least a rudimentary understanding of.

You don’t really need to know the exact differences between HDMI 2.1a and HDMI 2.1b, but it is crucial to get to grips with some of the major features. If you get the wrong standard HDMI cable, you could end up with no picture on your TV at all.

This is especially important if you want to make the most of your AV and gaming equipment as we near 2025, with the likes of the PS5, Xbox One Series X and the latest 4K UHD and 8K smart TVs all having different demands when it comes to using the right HDMI cable.

Despite all these issues, though, HDMI connections have endured. Mostly because for all their issues, they’ve remained almost endlessly upgradable, keeping pace with not just the demands of the AV world but, as we’ll see, the world of the smart home, too.

It’s also true, of course, that HDMI cables were designed with the best of intentions: to provide a single-cable digital video and audio solution.

Nonetheless, it’s clear that plenty of HDMI nonsense has happened along the way.

So here we attempt to pick through the HDMI myths to provide only the facts that you really need to know and help you choose the best HDMI cable, whether it’s for your gaming console, cable box, AV receiver, soundbar, or whatever else you want to plug into your TV.

Why aren’t all HDMI connections the same?

HDMI ports deal in digital data. And since the demands placed on digital data change much faster than things did in the analog age, HDMI connections and cables keep having to evolve too.

So quickly has HDMI had to adapt, in fact, that there a number of different generations of HDMI port are simultaneously playing a key part in today’s AV world. In fact, sometimes a single product can carry multiple generations of HDMI.

The main HDMI generations you need to concern yourself with if you’re thinking of buying a new AV product now are v1.4, v2.0, and v2.1. Let’s look at each in turn.

What is HDMI 1.4?

HDMI v1.4 was a big deal when it debuted in 2009 because it was the first HDMI platform with enough data bandwidth for 4K picture resolutions. It can, though, only shift enough data to support 4K at up to 30 frames a second.

Similarly, while it supports high dynamic range playback, that support is restricted with 4K to 8-bit color quality, rather than the 10 or 12 bit support offered by later HDMI versions.

Some legacy devices such as cable and satellite set top boxes, the original PS4, projectors and many relatively affordable TVs still carry these relatively affordable ports.

HDMI v1.4 also introduced the HDMI Ethernet Channel (HEC). This allows two connected devices to share a wired Internet connection – potentially very handy for smart home installations.

What is HDMI 2.0?

While HDMI 1.4 is still present in some devices, especially budget-friendly options, the majority of modern TVs and devices are these days come with HDMI 2.0 or newer versions.

The v2.0 HDMI provides much more bandwidth – chiefly so that it can better handle 4K video.

Its 18Gbps throughput is enough to support 4K at frame rates of up to 60Hz, as well as high dynamic range video up to the wide ‘Rec 2020’ color space with 10/12-bits of color resolution.

Also introduced with HDMI 2.0 was support for up to 32 audio channels at a high 1536kHz sampling frequency, and as many as four simultaneous audio streams and two simultaneous video streams.

HDMI 2.0b additionally added playback of the new Hybrid Log Gamma format already used by the BBC and expected to be taken up by other broadcasters soon.

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Over the past few years some brands have been able to squeeze some features associated with the HDMI 2.1 standard into HDMI 2.0 bandwidths.

Sony, for example, managed to get eARC lossless sound technology working over HDMI 2.0 (see the HDMI 2.1 section for more on this), while Samsung has managed to support the AMD Freesync variable refresh rate gaming system without needing a 2.1 HDMI port.

This has led to some confusion over the usual HDMI naming/numbering conventions, with essentially 2.0 HDMIs getting referred to in terms of HDMI 2.1 features they might support.

What is HDMI V2.1?

Formally launched in 2017, the v2.1 HDMI is the single biggest step forward for HDMI technology to date, with its massively increased 48Gbps maximum data rate opening up the potential for exceptional picture and sound quality, as well as innovative new features.

Unfortunately, though, it has also become by far the most complicated HDMI generation to date, thanks to a combination of displays ‘running ahead’ with some 2.1 features and claims before they’ve been fully ratified, and the potential for HDMIs of widely differing specs to be called HDMI 2.1.

Looking at the sort of new features HDMI 2.1 supports, as well as handling 4K images at frame rates of up to 120Hz, it can play video resolutions of up to 10K at lower frame rates (including 8K at 60Hz), paving the way for the next generation of 8K-resolution TVs.

It also supports so-called Dynamic HDR, where extra scene by scene information is provided to displays to help them show their HDR pictures better. Though dynamic HDR technologies such as Dolby Vision and HDR10+ had already been available via some HDMI 2.0 and even (in Dolby Vision’s case) HDMI 1.4 connections.

HDMI 2.1 introduces some key gaming features, such as variable refresh rate support to tackle image lag, stuttering and frame tearing; quick frame transport to help screens display images faster; and an Automatic Low Latency Mode feature that can trigger displays to automatically switch into their fast-response game modes when a game is detected.

HDMI 2.1 also improves the HDMI Audio Return Channel feature. Its ‘eARC’ version supports bandwidths big enough to carry lossless (uncompressed) object based sound formats, such as the purest versions of Dolby Atmos and DTS:X carried on Blu-ray and 4K Blu-ray discs.

The trouble with HDMI 2.1 is that its implementation has become very fragmented between different displays, with different TVs and TV brands claiming support for various HDMI 2.1 features, rather than everyone just using a single HDMI 2.1 standard that covers ALL HDMI 2.1’s potential capabilities.

Much of this potential confusion is down to manufacturers deciding to support different data rates with their various HDMIs, where the data rate can dictate the level of HDMI 2.1 features that can be supported.

The upshot of this is that you if you see a TV claiming to carry one or more HDMI 2.1 sockets (it’s common, just to confuse you more, for TVs to carry different HDMI ‘generations’), don’t assume that it will necessarily provide all the features HDMI 2.1 is capable of.

Look for some sort of itemised breakdown of which specific HDMI 2.1 features it can deliver, especially as HDMI 2.1a is now pretty standard for modern AV and gaming tech.

HDMI 2.1a or HDMI 2.1b: What’s the difference?

Adding to the confusion is that you will often now often see references to HDMI 2.1a or HDMI 2.1b.

We did warn you things were messy.

Basically, HDMI 2.1b is the latest standard, launched in August 2023 and, along with a few extra bells and whistles, it’s essentially designed to cut through some of the mixed messaging from brands introducing varying features with 2.1 and 2.1a, and make it clearer to consumers that they are getting the latest, greatest, standards.

All three require the same Ultra High Speed HDMI cable.

HDMI 2.1a introduced Source-Based Tone Mapping (SBTM), which dynamically optimizes HDR content directly from the source device (e.g., gaming consoles, streaming devices) rather than the TV.

HDMI and CEC

One potentially useful trick of HDMI cables for smart home applications is CEC.

Short for Consumer Electronics Control, CEC lets you control multiple devices connected via HDMI using only one remote control. So, for instance, if you connect a CEC-enabled Blu-ray player to a CEC-enabled TV, you will get extra menu options that let you use your TV remote to control Blu-ray playback.

Since the arrival of HDMI 2.0, CEC has had the potential to drive up to 15 devices via a single remote control.

CEC can currently be clumsily implemented or hard to follow on many devices, though – and many consumers don’t even know it exists. A concerted industry-wide push of CEC technology would likely help CEC realise its full smart home potential.

HDMI cables: What you need to know

As with HDMI connections, different HDMI cables can carry different amounts of data. So if you just buy the cheapest HDMI cable you can find, it may not give you all the features you want. For instance, if an HDMI cable can’t carry at least 40Gbps of data, it won’t be able to support 4K at 120Hz gaming.

To try and make life easier, the HDMI.org has established three HDMI ‘standards’ for you to look out for when trying to buy an HDMI cable.

Basic ‘category 1’ HDMI cables are not designed to carry the 18Gbps data rates associated with today’s HDMI 2.0 4K/HDR connectivity. As a result, while they can cost mere pennies, they’re probably best avoided now if you have any interest in 4K/HDR picture quality, or HDMI’s latest CEC ‘smart home’ capabilities. Limited to 1080p, these cables are unsuitable for modern 4K and HDR content.

Category 2 HDMI cables – also known as High Speed HDMI cables – are designed to handle the 18Gbps required to unlock HDMI v2.0 features. Category 2/High Speed cables should be labelled as such on their retail information. Required for 4K HDR, these cables are sufficient for most consumer setups.

The newest HDMI 2.1 format depends on data rates far higher than HDMI 2.0’s 18Gbps. In fact, it needs as much as 48Gbps. So to cater for this you’ll need what’s called an Ultra High Speed HDMI cable capable of handling such huge amounts of data. These cables are mandatory for HDMI 2.1’s 48Gbps, necessary for 4K at 120Hz and 8K playback, as well as VRR gaming. Look out for certified Ultra High Speed cables for assurance.

Should you buy Premium Certified/Ultra Certified HDMI cables?

While all HDMI cables should tell you at point of retail whether they are basic, High Speed or Ultra High Speed cables, that doesn’t mean that they’ve all been formally assessed by the HDMI Licensing group as definitely delivering all the features they promise. In fact, the vast majority will not have received official certification.

Uncertified High Speed and Ultra High Speed cables should all work fine, to be clear – but if you want absolute 100% peace of mind, you could look out for cables that have officially passed the official High Speed and Ultra High Speed compliance tests established by HDMI Licensing.

They display certification badges with QR codes for easy verification, a feature introduced in 2023 due to rising data needs and compatibility challenges.

Looking out for officially certified cables is particularly recommended if you need a relatively long cable run (5m or more).

The ‘Premium Certified’ badge for HDMI cables was created by the HDMI Licensing Group to show that a cable has passed the organisation’s internal 18Gbps tests. The Ultra Certified Cable badge was created to show where a cable has passed the organisation’s internal 48Gbps tests.

Note that while Premium Certified cables have been widely available for some time, it was only in September 2020 that the first Ultra High Speed HDMI cable was officially certified – the best part of three years after the first Ultra High Speed HDMI cables went on sale.

What are Active HDMI cables?

Most HDMI cables are passive, and can pass their signals in either direction. Active HDMI cables, though, only send their video signal in one direction. Why? Because they contain power boosters that amplify the signal coming from your source as they send it on its way.

For most HDMI cable runs an active HDMI cable won’t be necessary. However, if you need to use a really long cable run (likely 25 feet or more), an Active HDMI cable may make the difference between a data-intensive signal making it or not, as HDMI cables generally become less reliable the longer they are.

Active HDMI cables are potentially more likely to be useful for smart home applications based on CEC technology than typical video set ups.

Are expensive HDMI cables worth it?

You can spend thousands of pounds even on quite short HDMI cables. But there’s doesn’t seem to be any compelling reason to do so.

Unlike the analogue world, where higher quality analogue cables can deliver superior audio or picture results, HDMI’s digital nature essentially means that cables either carry enough zeroes and ones from one end to the other to deliver a video signal, or they don’t.

It’s worth noting that pricier cables can sometime offer enhanced durability or specific layouts for professional use cases.

Some relatively expensive cables also offer handy tricks such as extra-strong mounts, or smart home-friendly flat cable profiles for running under carpets.

Also, if you’ve got a very long cable run and a 4K or even 8K screen to feed, it is possible that a relatively expensive cable will carry all that signal bandwidth more consistently/successfully.

Cables that have received official certification from the HDMI Licensing group may cost a little more, too.

None of these premium options, though, need to cost hundreds or thousands of pounds.

The best HDMI cables to buy

Best budget HDMI cable: Amazon Basics High-Speed HDMI Cable

Coming in a range of sizes from 6 feet to 25 feet, Amazon’s cheap-as-chips HDMI 2.0 compatible cable is a great budget option that supports 4K@60Hz and HDR. It’s a reliable choice for most people who don’t need the absolute highest performance.

Best for 4K gaming: Monoprice Premium Certified High-Speed HDMI Cable

This cable is a great choice for gamers who want the best possible performance for their 4K gaming setup. It supports 4K@120Hz and VRR, ensuring smooth and responsive gameplay. There are six lengths to choose from.

Best for 8K and high-end home theater: AudioQuest 48G Vodka eARC Priority HDMI cable

The AudioQuest 48G Vodka eARC Priority HDMI cable is a high-performance HDMI cable designed for demanding home theater setups. It supports 8K resolution at 60Hz and 4K resolution at 120Hz, making it ideal for the latest 8K TVs and gaming consoles. It features AudioQuest’s proprietary noise-dissipation technologies, including Level-3 Noise-Dissipation, to ensure optimal signal transfer and minimize interference. Additionally, the eARC-Priority design prioritizes the Enhanced Audio Return Channel (eARC) connection, allowing for high-resolution audio formats to be transmitted from your TV to your audio system. If money is no object and you’re looking to future-proof then this is the answer.

Best HDMI 2.1 cable under $20: Anker 8K HDMI Cable

This premium but affordable HDMI 2.1 cable delivers stunning visuals with 8K resolution at 60Hz or 4K at 120Hz, thanks to its 48Gbps bandwidth. Certified by the HDMI Forum, it supports VRR, QFT, ALLM, QMS, and eARC for an immersive gaming experience. Its sleek design with carbon steel connectors and a durable nylon braid adds to its appeal.

Best right-angle, 90-degree HDMI cable: UGreen 90-Degree HDMI Cable

If your TV is mounted flush to the wall and your HDMI ports aren’t in a dedicated sideways section then you may find a HDMI cable makes your TV stick out, or go wonky. That’s where a right-angle HDMI cable comes in, and this option from UGreen can handle any HD content, and 4K up to 30fps.

HDMI FAQs