HDMI 2.1 explained: bandwidth, 4K 120Hz, cables and ports

HDMI is the cable standard that carries picture and sound between your TV and everything plugged into it. HDMI 2.1 is the version gamers and home theater buyers usually mean when they ask whether a TV is "future-proof". It matters because of what it makes possible, and because not every HDMI 2.1 TV delivers all of it on every port.

What HDMI 2.1 added

According to the HDMI Licensing Administrator, which licenses the standard, the Ultra High Speed cable arrived alongside HDMI 2.1 and reached stores in 2020. It is meant for setups needing up to 48Gbps of bandwidth. Bandwidth is the amount of data a connection can carry each second, and higher resolutions and refresh rates need more of it.

The features people care about are mostly for gaming:

• High refresh rates. The HDMI Forum's current resolution page lists 4K at 120Hz among the supported formats.
• Variable Refresh Rate (VRR). The game console or PC sends frames as they are ready, which the organization says reduces lag, judder and tearing. See our VRR and input lag explainer.
• Auto Low Latency Mode (ALLM). The TV switches to its low-latency game mode automatically when a console starts, then switches back for movies.
• Quick Frame Transport and dynamic HDR support. Both are part of the same toolkit.

The HDMI organization notes that the PlayStation 5 and Xbox Series X were the first consoles to support these gaming features, and that several graphics cards from Nvidia, AMD and Intel do as well.

HDMI 2.2 is here, but most buyers can skip it

HDMI.org now presents HDMI 2.2 as the latest version. It raises the ceiling to 96Gbps and adds support for 8K at 60Hz, 4K at 240Hz with full color detail, and resolutions up to 16K. It comes with a new Ultra96 cable, and the organization states that only this cable supports all HDMI 2.2 features. If you are buying a 4K TV today, 2.1 features cover current consoles, and a 48Gbps cable is the sensible match.

Why the ports on your TV may differ

The same TV can have several HDMI ports, and they do not always offer the same features. TechRadar's gaming guide lists, for each TV, the number of HDMI ports and how many of them are HDMI 2.1. The LG C6 and Samsung QN90F are shown with four HDMI 2.1 ports each, which means you can plug in a console, a PC and a soundbar without swapping cables. Other models can have fewer ports with full features, which is why the count is worth checking.

Two practical checks follow:

1. Read the spec sheet or manual for which ports support 4K 120Hz and VRR, and use those for your console and PC.
2. Check the port a soundbar uses. TechRadar notes that some soundbars lack HDMI passthrough or 4K 120Hz passthrough, which is a problem if you also want to connect a console. The usual fix is to connect the console to the TV directly and send audio to the bar over eARC; our eARC explainer covers that.

You can compare how many full-speed ports a model offers with the compare tool, or read specs on pages such as the LG C6, Samsung QN90F and TCL QM6K.

Picking a cable

Cable marketing is confusing, and the HDMI organization says it is common for sellers to use unofficial names. Some cables are counterfeit. Its guidance is to look for the official name, Ultra High Speed HDMI Cable, printed on the cable jacket, and for the certification label on the package. The label carries a QR code you can scan to verify the model was tested at an authorized test center, and the program also tests for low interference with wireless devices such as Wi-Fi and Bluetooth.

For most living rooms, a certified Ultra High Speed cable at the shortest length that reaches is enough. Very long runs behind walls are a separate problem, and a professional installer can advise on in-wall rated or fiber options.