The HDTV aspect ratio is 16:9 (pronounced "sixteen-by-nine"). Aspect ratio is the ratio of the width of an image to its height, and is always expressed as two numbers separated by a colon. Aspect ratio defines the shape of an image -- not the size. The HDTV aspect ratio of 16:9 means that the image (or screen) is sixteen units wide and nine units tall. The "units" can be any unit of measurement -- inches, feet, centimeters, or even toothpicks -- as long as you have sixteen of them aligned horizontally and nine aligned vertically.

As a comparison, the old TV system (NTSC) and the current standard TV (SDTV) both have aspect ratios of 4:3 ("four-by-three"), meaning the screen is four units wide and three units tall. Relative to the HDTV aspect ratio, SDTV is rather square and boxy.

So, why is the HDTV aspect ratio 16:9 and not some other seemingly arbitrary shape like 16:10 or 15:8? The reason is that the HDTV aspect ratio of 16:9 is the geometric mean of the most extreme film and TV aspect ratios. Considering the fact that there are numerous film and television formats ranging from the boxy 4:3 aspect ratio of SDTV to the extremely wide-screen 2.35:1 ("two-point-three-five-by-one") aspect ratio of CinemaScope, the HDTV aspect ratio of 16:9 was determined to be the best shape to incorporate the majority of data contained in all of the various formats. While the HDTV aspect ratio of 16:9 was initially selected as a compromise, the subsequent popularity of the 16:9 HDTV aspect ratio has established it as the most important video aspect ratio for the future.

Optimum HDTV Viewing Distance and Screen Size

One reason for the popularity of the 16:9 HDTV aspect ratio is that the screen is wide enough (and the image is also clear enough) to provide an immersive visual experience similar to that in a movie theater. Although HDTV manufacturers have so-called "optimum HDTV viewing distances" for their HDTV sets, the fact is that the HDTV picture is so clear that you can sit as close to the screen as you feel comfortable. The closer you are, the more it fills your field of vision, and the more immersive the viewing experience. (This was impossible with the old NTSC system because the picture was not clear enough to view up close, and not wide enough to fill your field of vision.)

In actuality, the optimum HDTV viewing distance stated simply is "as close as you can stand it!" Accordingly, the best HDTV screen size for you is the largest screen you can possibly afford, and the bigger the better! Another way to look at it is to visualize your living room (or viewing room) as a movie theater. How big should the screen be in relation to your room? The bigger the better, right? So, forget the manufacturers' recommendations for optimum HDTV viewing distances and get the biggest screen you can afford. The 16:9 HDTV aspect ratio combined with the high definition clarity will provide you with the most immersive home viewing you can experience.

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Founder of HD Pictures, Stuart Calcote is a 29-time Emmy Award winning producer/director of international television programs and one of the first in the world to produce programs in HDTV. Visit calcote.com for more information about Stuart Calcote.

© 2010 Stuart Calcote. All rights reserved.