In theory, there is no real maximum length to how long an HDMI cable can be. But the longer your cable is, the more the type of HDMI cable you buy can have a real impact on the eventual quality of audio and video you hear and see at the other end.
How long can an HDMI cable be? It depends on how it's made and what resolution your content is. The longer an HDMI cable is, the more signal it loses due to attenuation, which is why it needs to be made with a thicker gauge, officially known as its AWG rating; its American Wire Gauge. The lower a cable's AWG rating, the thicker its gauge and the better equipped it is to deliver a high-resolution signal over longer distances. For example, a thin cable won't be able to transmit a 4K signal as long as a 1080p signal.
The maximum length for passive HDMI cables
If you're just looking to buy a passive HDMI cable, then your realistic maximum range is around 25ft. Cable Matters sells a wide variety of options in that category. Slim HDMI cables, premium HDMI cables, HDMI cables with 90-degree headers, and even retractable ones for making sure you only let loose as much cable as you absolutely need.
Whichever one you opt for though, 25ft is about the maximum length you can use without seeing a degradation in signal quality due to attenuation. Although passive HDMI cables can support distances more than twice that in theory, the environment would need to be practically perfect to not experience severe negative consequences of such a long cable without some sort of active power to counteract the signal degradation.
For longer cables, you need something more robust.
The maximum length for Active Optical HDMI cables
If you're looking to hook up ceiling-mounted projectors or building a home movie theatre with the media stored far from the eventual display, you'll need a relatively lengthy and hefty HDMI cable for the job. That's where you'll run into problems with standard, low-cost HDMI cables. Instead, you want to use something like the active fiber optic HDMI cable.
It supports HDMI 2.0 and has a fire-rated cable jacket and is fully certified to be routed through ductwork or walls. These cables are light and flexible, making them a great choice for getting to hard to reach places. You’ll find lengths ranging from 10 to 30 meters (close to 100 feet) for these cables.
If that's still not enough for you though, there are ways to double, or even triple that range.
HDMI Extenders boost range to 300 feet
Once you reach extreme ranges in the multiple hundreds of feet, a singular cable just isn't going to cut it. You'll see weakened signals causing instability and screen flashing, alongside other image degradations. On the other hand, we know the answer to the question, “How long can an HDMI Cable be?” is theoretically as long as you want- just keep increasing the wire gauge. However, at a certain point wire gauge becomes too thick to be useful. HDMI extenders can solve that problem.
HDMI extenders offer ranges up to 300 feet and compress the HDMI signal to send it over a lengthy Ethernet cable instead. In theory, extenders based on optical fiber technology can extend an HDMI signal to almost 1,000 feet, but it's not typically recommended unless in extreme scenarios where no other options are available.
You don't need to be concerned about a loss of features or quality over more reasonable distances, though. High-quality HDMI 2.0 extenders can transmit 4K resolution at up to 60Hz up to 164ft without difficulty. They also fully support HDR, 10-bit color, and both HDCP 2.2 and HDCP 1.4 for viewing protected content.
If you're looking to install a display in a public setting too, you can use the extender to connect to a local, as well as a remote display, making it easy to see what's being viewed on the main display from a backroom or office. Built-in infrared cables ensure that any commands you send to that local display can also be mirrored on the remote one too.
Note: It's a good idea to use a Cat6 Ethernet cable with these extenders as it will provide the best signal at your display. Older, Cat 5 or Cat 5e cables may be usable, but the signal won’t travel as far as with a Cat6 cable.
If you want to make things neat and tidy, why not consider running your lengthy HDMI connection to a dedicated wall plate? In sum, if you find yourself asking “How long can an HDMI cable be?” then it may be time to consider an HDMI extender.
What resolutions can HDMI cables handle?
HDMI technology is licensed under a number of different specifications, depending on the quality of the cable. Standard cables are certified up to 720p resolution, while high-speed options can support 4K and HDR. Almost all of Cable Matters' HDMI cables support 4K and HDR natively, as only the highest quality of cables are sold to guarantee a strong customer experience. There are some alternatives that end in different headers, like VGA, or DisplayPort, which have their own limitations on resolution and refresh rate, outside of the HDMI specifications.