Viewing 4K via Comcast Cable: What You Need to Know

COMCAST cable offers 4K viewing, but the selection is limited

Illustration of a 4K television and an Xfinity cable box

Lifewire / Derek Abella 

With the inevitable march of technology, the 4K offerings from Comcast's Xfinity cable service for your 4K Ultra HD TV continue to increase, and they're available in all markets where Comcast has a license to operate.

What You Need to View 4K on Comcast Infinity Cable

To view 4K via Comcast, you have to line up a few things first:

  • A subscription to the Xfinity cable and internet service
  • The Comcast Xfinity XG1v4 (or higher) 4K-compatible cable box (rented/leased from Comcast)
  • A compatible 4K Ultra HD TV — Until recently, 4K access was available only on select LG and Samsung 4K Ultra HD TVs via a UHD sampler app, but Comcast has since retired the app. If subscribers have the required XG1v4 (or newer) cable box, almost all 4K Ultra HD TVs are compatible. If you have questions regarding compatibility of your TV, contact Comcast Support.

Where to Find Content

Once you have committed to subscribing to Xfinity and renting the box, you will have the ability to access 4K content offered by Comcast from two content sources:

  • Netflix: Netflix 4K content is delivered through the internet via streaming, in the same way as it would be available using a standalone or plug-in media streamer or through a compatible 4K Ultra HD smart TV: a fast internet connection. The programming selection is the same as through those options. To watch this content, you must also have a current, paid Netflix account exclusive of any fees you pay for your Comcast plan.
  • Comcast Xfinity's in-house on-demand service: Via on-demand, subscribers can select from a limited number of films and TVs shows, the selection of which periodically changes. Also available are special events that may be presented on a delayed basis, instead of a live broadcast — for example, the Olympics and other high-profile sporting events. The 4K programming is rotated in and out on an intermittent basis, so if you notice something you would like to watch, do so ASAP; it might not be available for long.

The XG1v4 Box

The XG1v4 is not available for self-installation; an installer housecall is required.

Here are the core features of the required XG1v4 Box:

  • 4K and HDR (HDR10) compatibility: Also compatible with SD and HD programming
  • Six tuners: Built-in for flexible viewing and recording options
  • 500GB hard drive: Offers temporary storage of recorded videos (recording in 4K supported)
  • One HDMI output for video/audio connection to TVs and home theater receivers (but no component or composite video outputs or additional digital optical/coaxial or RCA analog audio output options)
  • One RF cable input and one RF cable output: 4K cannot be accessed via the RF output. Refer to slides 9 and 10 in our Home Theater Connection Gallery for RF cable examples.
  • Ethernet port: Allows connection to a network router that provides access to Netflix and any other available or required Internet-based features
  • Bluetooth support: Allows users to stream audio through the box from compatible devices (such as a smartphone); also allows users to stream music to compatible Bluetooth headphones and speakers (one device at a time)

The XG1v4 also has one HDMI input; however, it is not active, so you can't use it as a pass-through connection for additional HDMI devices. This has resulted in both puzzlement and anger among some Comcast subscribers, who would like this feature enabled for its designed purpose.

The Bottom Line

Ever since 4K Ultra HD TVs were introduced, availability and sales have increased steadily, with a corresponding trend toward affordable pricing. This has resulted in millions of consumers having and using these sets. Although sets are plentiful and affordable, the pace of 4K content delivery for viewing has lagged behind demand.

Likewise, while 4K content on Ultra HD Blu-ray disc and via streaming services such as Amazon, Netflix, Vudu, and others has increased steadily, 4K TV broadcasting is still a ways away. DirecTV and Dish Network offer limited 4K content via satellite, but 4K over cable is almost non-existent. Comcast/Infinity is the only major cable provider offering limited 4K content access.