Resolution describes the sharpness of the TV picture, usually in terms of horizontal lines of pixels. They’re very rare at this point and should be avoided, but a bargain HD set may support only 720p, which means the set displays 720 lines scanned progressively (or in a single pass). Other HDTVs support the 1080p HD format, also called full HD, which has 1,080 lines of resolution. But at this stage, we’d skip 1080p sets, too.
That’s because TV manufacturers are rapidly shifting from HDTVs to Ultra HD sets (also called 4K). These 4K models have four times the number of pixels as current HDTV screens. We’re talking 2,160 horizontal lines, or 3840 x 2160 pixels. The biggest benefit of 4K TVs is that small objects on the screen have more detail, including sharper text. Overall, images appear richer and more life-like than on an HDTV, but the benefits can be subtle.
Ultra HD video looks great, if you can find it — there are no 4K broadcast or cable channels and only a handful of streaming options available so far (most notably, a few programs from Netflix, rentals from Amazon and specialty services such as UltraFlix; Dish Network and DirecTV are rolling out 4K download services). Although Ultra HD sets can upscale existing HD content, the results can be mixed and do not look as sharp as original 4K programming.
With those provisos, ultra-HD TV models are supplanting conventional HDTVs. Vizio, for example, has only one HDTV line left.
Bottom Line: Full HD 1080p is still the most common screen resolution today, but 4K is increasingly becoming the standard, and it’s a better choice if you want to future-proof your investment.