The truth about Ultra HD 4K TV refresh rates

There's a simple rule of thumb for companies that market electronics: When it comes to specs, a higher number usually preferred. Sure, there are exceptions -- you want things like response time, load times and mobile device weight to be low -- but generally, more equals better. It comes down to the "speeds and feeds" aspect that still dominates a lot of tech shopping: when you line up a bunch of similar TVs, phones, laptops or tablets, the ones with the higher numbers get the edge. Think about battery life, display resolution, screen size, processor speed, memory and storage capacity -- just to name a few.

Of course, the quoted number is often only half the story. Consider the megapixel myth of digital cameras: a 15-megapixel camera isn't necessarily going to yield a "better" picture than a 8-megapixel shooter. Nor is a 4K Ultra HD TV -- with resolution of 3,840 x 2,160 -- going to necessarily outshine a "standard" HDTV with 1,920 x 1,080 pixels, or just one-fourth of the 4K screen's resolution. Plenty of other factors, including color accuracy and contrast ratio (not to mention the quality of the video source) will affect the picture quality to a normal eye.

Then there's refresh rate. The spec refers to the number of times per second that a video screen is updated, with a higher number yielding a smoother, more natural-looking motion (to a point). The baseline for this number was set back in the last century, with movie projectors hitting 24 frames per second (expressed as a frequency in Hertz, or Hz), and old standard-definition TVs set at 60 Hz (or 50 Hz, in many countries outside the US).

In the HD era, though, TV manufacturers started an arms race of sorts, ramping up refresh rates in increasing multiples to 120 Hz, and even eventually 240 Hz. There was even a time where some plasma TVs were claiming (somewhat dubiously) a 600 Hz refresh rate of sorts. (The "more equals better" situation again.)

So, now that we're in the post-HD 4K TV era, we're clearly up to 480 Hz, right? Or possibly 960 Hz?

Not exactly. The fact is that nearly all of these new 4K TVs -- which now make up the increasing majority of all TVs priced over $1,000 -- have, at best, a 120 Hz refresh rate. Actually, many of the least-expensive are actually 60Hz, and none that we know about are 240 Hz.

So, you may be asking yourself, what's with all the 4K TV marketing that claims numbers of 240 or even higher? Well, they're fluff. Very carefully worded marketing fluff, in most cases.

But does that mean those of you trading in a recent 240Hz 1080p TV for a bigger, sub-240Hz 4K Ultra HD TV are actually downgrading your picture quality?