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In four years of TV evolution, 4K resolution has gone from a questionable upgrade to a near-standard feature. Buy a set bigger than 50 inches, and it’s now overwhelmingly likely to feature "Ultra High Definition" resolution (3840 by 2160 pixels) instead of mere HD (1920 by 1080 pixels). 

But finding something to watch in 4K (named for those almost 4,000 pixels of horizontal resolution) is not such a sure thing, and your two best options may require upgrading your Internet connection or the rest of your home-theater rig.

Bandwidth

Online streaming remains the biggest source of 4K content, led by Netflix and Amazon’s growing selection of original series. But many consumer broadband connections aren’t fast enough to allow reliable 4K streaming. 

Amazon recommends at least 15 megabits per second, while Netflix advises 25 Mbps. But if other devices at home will be occupying your bandwidth, 15 or 25 Mbps alone won’t suffice. 

And for some customers, that’s not an option at all: The Federal Communications Commission’s most recent statistics show that as of the middle of 2016, 21% of census blocks didn’t have a single provider offering 25-Mbps or faster downloads.

If your Internet provider imposes a data cap, remember that 4K streaming’s appetite for data — Netflix estimates 7 gigabytes an hour — can push you past that limit.

That is five times the bandwidth the company recommends for high-definition streaming. Trading up to that speed may not cost much extra if you have cable: At one San Francisco address, Comcast’s 55-Mbps service only cost $15 or so more a month than its entry-level 10-Mbps offering, with the difference even less when factoring in promotional discounts.

But it will probably require changing ISPs if you have phone-based digital-subscriber-line broadband, which rarely gets past 10 Mbps. 

Internet alternatives

Since early 2016, the Blu-ray disc format has offered an offline alternative for 4K viewing. But the selection of 4K Blu-ray remains a tiny fraction of what’s available in that format’s older HD version. Best Buy’s site shows 324 4K Blu-ray titles versus 14,563 standard Blu-ray discs. 

If you have a soundbar set up as the hub of your home-theater setup — with the TV plugged into its outputs and your streaming-media or Blu-ray player plugged into its inputs — you will also need to replace that with one that includes “HDMI 2.0” ports compatible with 4K.

Cable or satellite TV, meanwhile, probably won’t help you watch any 4K content. DirecTV does offer 4K channels, but its schedule shows only 13 live events for the rest of December. At Comcast, your only 4K options for now are two streaming apps, Netflix and its own Ultra HD Sampler, that you can run on an upgraded version of its X1 box.

"Technology is leading content," summed up analyst Roger Entner, founder of Recon Analytics. "They’re still waiting for content."

Broadcast TV is limited to HD today, but the Federal Communications Commission voted in November to let broadcasters start airing signals in the 4K-compatible “ATSC 3.0” format. But since no U.S.-market sets ship with tuners for that standard — also called "Next-Gen TV" — you shouldn’t expect local stations to rush to broadcast in it.

You can always watch your existing channels, streaming apps and discs on a 4K set. But if much of that content is not in HD but standard definition, a 4K set’s attempt to scale up that resolution to match its own may make it look worse than it does on a regular high-def TV.

Rob Pegoraro is a tech writer based out of Washington, D.C. To submit a tech question, e-mail Rob at rob@robpegoraro.com. Follow him on Twitter at twitter.com/robpegoraro.