What It Is an Aspect Ratio and Why It Is Important?

LG UH6500 4K UHD TV with TV and Movie Aspect Ratio Chart
LG UH6500 4K UHD TV with TV and Movie Aspect Ratio Chart. Images provided by LG and Wikimedia Commnons (Public Domain)

Screen Aspect Ratio Defined

The home theater experience isn't complete without a TV or video projector to view your favorite TV programs, movies, and streaming content on. When going to the local consumer electronics retail store to pick out a TV, the potential buyer is sometimes overwhelmed by the sheer selection and sizes of TVs to choose from. Not only do TVs come in big and small sizes, there is also another factor to be aware of: Screen Aspect Ratio.

Screen Aspect Ratio represents the horizontal width of a TV or Projection screen in relation to it its vertical height. For example, most older analog CRT TVs (some are still in use) have a screen aspect ratio of 4x3, which gives them more of a squarish appearance.

What this means is that for every 4 units in horizontal screen width, there are 3 units of vertical screen height.

On the other hand, since the introduction and of HDTV (and now 4K Ultra HD TV), TV screen aspect ratios have changed to a 16x9, which means that for every 16 units in horizontal screen width, the screen has 9 units of screen height.

In cinematic terms, these ratios are expressed in the following manner: 4x3 is referred to as a 1.33:1 aspect ratio (1.33 units of horizontal width against 1 unit of vertical height) and 16x9 is expressed as a 1.78:1 aspect ratio (1.78:1 units of horizontal width against 1 unit of vertical height).

Diagonal Screen Size vs Screen Width/Height For 16x9 Aspect Ratio TVs

Screen width and height provides the consumer the primary information on how a TV will fit within a given space (excluding any additional TV bezel and stand dimensions) - but when you shop for a TV, the main information that is provided in Ads is the diagonal screen size.

To further aid in purchasing a 16x9 Aspect Ratio TV, here are some common diagonal screen sizes, translated into screen width and height (all numbers in inches):

  • 32(Diagonal) = 27.9(W) x 15.7(H)
  • 40(Diagonal) = 34.9(W) x 19.6(H)
  • 42(Diagonal) = 36.6(W) x 20.6(H)
  • 43(Diagonal) = 37.5(W) x 21.1(H)
  • 46(Diagonal) = 40.1(W) x 22.6(H)
  • 47(Diagonal) = 41.0(W) x 23.0(H)
  • 50(Diagonal) = 43.6(W) x 24.5(H)
  • 55(Diagonal) = 47.9(W) x 27.0(H)
  • 60(Diagonal) = 52.3(W) x 29.4(H)
  • 65(Diagonal) = 56.7(W) x 31.9(H)
  • 70(Diagonal) = 61.0(W) x 34.3(H)

Aspect Ratios and TV/Movie Content

With LED/LCD and OLED TVs now the types available (CRT TVs are now very rare, Rear Projection TVs were discontinued in 2012 and Plasma was discontinued in late 2014), the consumer now needs to understand the 16x9 screen aspect ratio.

TVs with a 16x9 screen aspect ratio are more suited to the increasing amount of 16x9 and other widescreen programming available on DVD and HDTV broadcasts.

However, there are still some consumers are more used to the older 4x3-shaped screen.

However, with a vast amount of programming now available in widescreen formats, owners of older 4x3 TVs are watching a growing number of TV programs and DVD movies with black bars on the top and bottom of their screens (commonly known as letterboxing).

Many viewers, not accustomed to this, think that they are being cheated by not having the entire TV screen filled with an image. This is not the case.

Although 16x9 is now the most common aspect ratio you will encounter for home TV viewing, there are many other aspect ratios that are used in both home theater viewing, commercial cinema presentation, and computer graphics display.

Most films made after 1953 were (and continue to be) filmed in various widescreen formats, such as Cinemascope, Panavision, Vista-Vision, Technirama, Cinerama, or other widescreen film format.

How Widescreen Movies Are Shown On 4x3 TVs

In order to show widescreen films so that they fill the entire screen on an older 4x3 TV, they are sometimes re-edited in a Pan-and-Scan format, with an attempt to include as much as the original image as possible. To illustrate this, take an example where two characters are talking to each other, but each is standing on opposite sides of a widescreen image. If shown full screen on a traditional TV without further editing, all the viewer would see would be the empty space between the characters.

To remedy this, editors must recut the scene for video release by jumping from one character to the other as they speak and respond to each other. In this scenario, however, the intent of the film director is severely altered, because the viewer does not see the entire composition of the original scene, including any facial expressions or body language in response to the other character who is speaking.

Another problem with this Pan-and-Scan process is lost impact of action scenes. An example of this is the chariot race in the 1959 version of Ben Hur. In the original widescreen theatrical version (available on DVD and Blu-ray - Buy From Amazon), you can see the entire impact of Ben Hur and the other chariot racers as they battle each other for positioning in the famed chariot race segment. In the Pan-and-Scan version, sometimes broadcast on TV, all you see is the camera cutting to closeups of the horses and reins. All the other action in the frame is totally missing, as well as the body expressions of the chariot riders.

For other illustrations of this issue check out Widescreen vs Pan & Scan by IGN.com, and 2.35 vs 2.40 Aspect Ratio.

The Practical Side Of 16x9 Aspect Ratio TVs

With the advent of DVD, Blu-ray, and HDTV, the appearance of TVs with screens more closely shaped to that of a theatrical movie screen are now standard on store shelves.

With the switchover to DTV/HDTV broadcasting now complete, as well as the introduction of high-definition Blu-ray, and now, Ultra HD Blu-ray, the switchover to TVs with a 16x9 Aspect Ratio is was an important decision.

Although the 16x9 aspect ratio may be best suited for watching motion pictures on video, all network TV (with very few exceptions) and even local news, has benefited from this design. Sporting events, such as football or soccer, are well suited for this format in that now you can get the whole field in one wide shot at a closer vantage point than the distant wide shots we have been used to.

16x9 TV, DVD, and Blu-ray

When you purchase a DVD or Blu-ray Disc, many times it is formatted for widescreen viewing. On DVD packaging you may notice the terms Anamorphic or Enhanced For 16x9 Televisions on the packaging. These terms are very important, and practical, for owners of 16x9 TVs.

What this means is that the image has been placed on the DVD in a horizontally squeezed format that, when played on a 16x9 TV, is detected and stretched back out horizontally in the same proportion so that the widescreen image is displayed in the correct aspect ratio without shape distortion.

Also, if a widescreen image is shown on a standard 4x3 television in letterboxed format, in which there are black bars at the top and bottom of the image. For a detailed explanation of how anamorphic DVD works, including illustrations, check out What is Anamorphic DVD? from DVD Beaver.

What About All Those Older 4x3 Movies and TV Programming

When viewing older movies or TV programs on a 16x9 aspect ratio TV, the image is centered on the screen and black bars appear on the sides of the screen as there is no image to be reproduced. There is nothing wrong with your TV - you are still seeing the entire image on the screen - it is just that since your TV now has a wider screen width, older content does not have any information to fill the entire screen. This definitely bothers some TV viewers, and, to get around this discomfort, some content providers may add white or patterned borders to fill the black screen areas.

However, it must also be pointed out that due to the various aspect ratios used in movie production, even on a 16x9 Aspect Ratio TV, TV viewers can still encounter black bars, this time on the top and bottom of the image - For more details, read my article: Why are Black Bars Sometimes Still Visible on my LCD, Plasma, or OLED TV?

Final Take and More Info

Home theater is getting more and more popular with consumers. Blu-ray, DVD, surround sound, and TVs with a 16x9 aspect ratio bring a more authentic audio/video experience to the living or entertainment room.

For more on how aspect ratio is applied to movie and TV content, check out the following additional sources:

The Letterbox /Widescreen Advocacy Page

Guide To Anamorphic Widescreen DVD

Widescreen Advocate

Widescreen Museum

Original Publish Date: 12/26/2005 - Robert Silva

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