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21:9 aspect ratio

21:9 (2.33:1) is the approximated screen aspect ratio of the true value 64:27 (2.370:1) in comparison to the common ratio of 16:9 (1.77:1). It is designed to show films recorded in CinemaScope or the modern anamorphic format of 2.39:1. The main benefit of this screen ratio is the absence of the black bars at the top and bottom of the screen when viewing content in this format, and a constant display height when displaying other content with a lesser aspect ratio.

The 64:27 aspect ratio is the logical extension of the existing video aspect ratios 4:3 and 16:9, as it is the third power of 4:3, where 16:9 of traditional HDTV is 4:3 squared. This allows electronic scalers to use an easily implementable 4:3 (1.33:1) scaling factor.

<math>\tfrac{4}{3} \cdot \tfrac{4}{3} = \tfrac{16}{9}</math>

<math>\tfrac{16}{9} \cdot \tfrac{4}{3} = \tfrac{64}{27}</math>

The term "21:9" was chosen as a marketing term, probably first used by Philips. Due to its common denominator, 21:9 is more relatable to 16:9, the aspect ratio of regular HDTVs, rather than the correct 64:27 or 21<math>\tfrac{1}{3}</math>:9. If it actually were 21:9, the fraction could be expressed more elegantly in the reduced form as 7:3.

Constant height

A 21:9 TV allows to display all content at equal height, allowing for a more balanced viewing experience.

16:9 TV 21:9 TV
16:9 content

16:9 content on 16:9 TV

16:9 content on 21:9 TV

21:9 content

21:9 content on 16:9 TV

21:9 content on 21:9 TV

Film formats and 21:9

Format Aspect ratio
Cinemascope (1950s–1970s) 2.35:1
"21:9" (64:27) 2.370:1
Anamorphic, modern cinema widescreen format 2.39:1



As of May 2013, video timings in this 64:27 aspect ratio are supported by the technical specification that defines video timings for the HDMI interface, CEA 861-F:[1]

  • 1280×720p, anamorphic pixel aspect ratio of 4:3
  • 1680×720p, near-square pixel aspect ratio of 64:27
  • 1920×1080p, anamorphic pixel aspect ratio of 4:3
  • 2560×1080p, square pixel aspect ratio
  • 3840×2160p, anamorphic pixel aspect ratio of 4:3

All of the above timings are supported at frame rates of 23.97/24, 25, 29.97/30, 50 and 59.94/60 Hz, as well as 100 and 119.88/120 Hz for the non-UltraHD timings.

An additional resolution of 5120×2160p ("5K") could be added at a later time to provide a non-anamorphic UltraHD signal in 21:9. Variations of the 8K UltraHD resultions could also be considered, at 7680×4320p anamorphic and 10240x4320p non-anamorphic.


The Ultra HD Blu-ray specification was reportedly[2] include support for anamorphic video in a 64:27 aspect ratio as well. Eventually, this feature was not included in the final specification.[3] The company Folded Space is working on a proprietary solution, MFE,[4] to put anamorphic 21:9 video onto Blu-rays in a way compatible with standard players.

Consumer Devices

Flat panel TV

All Blu-ray Disc content with 1920 horizontal resolution has 1080 vertical resolution, though in the case of widescreen formats wider than 16:9, the image appears on 16:9 displays with letterboxing. The Cinema TV eliminates the black bars by scaling the 1920 horizontal resolution to its full width of 2560 and the 800+ pixels of cinemascope images (actual pixel counts vary[5][6]) is scaled to 1080 with the black space cropped. The result is an image which fills the screen, but does not provide higher quality due to the use of scaling.[7] Despite the intention being to fill the screen with a non-letterboxed image, the zoom mode can result in some cropping at the edges.[8] Content with the full image at 1920×1080 can be displayed in the center of the screen with pillarboxing, and should the viewer choose to not display cinemascope content at full width, it appears windowboxed.


The Philips 'Cinema 21:9 TV' was the first LCD television of this aspect ratio.[9] The first model launched was a 56-inch screen size, although it was no taller than a conventional 16:9 42-inch television. Models released in 2010 and 2011 had a screen sizes of 50 and 58 inch.

Early reviews have claimed that it is "one of the coolest TVs" to enter the market for some time.[8] This set was previewed in the UK in advance of its release date of 18 June 2009. Pre-release launch events were held at numerous Philips retailers throughout June 2009.

The online advertising campaign surrounding the Cinema 21:9 TV, titled Carousel, went on to win the most prestigious award in the advertising industry, the Grand Prix at the Cannes Lions International Advertising Festival.[10]

In 2012, Philips stopped production on all its 21:9 televisions due to lack of demand.[11]


Vizio has since followed suit with their own Cinema TVs with identical resolution, similarly marketed as "21:9" in the United States.[12][13]

The 58-inch TV with a panel resolution of 2560×1080p has been sold in 2012 and 2013, and has since been discontinued. A planned 50-inch model never made it to market.


LG has a number of computer monitors with a panel resolution of 2560x1080 or 3440x1440 and a 21:9 aspect ratio, the 29EA93, 29EA73, 29LN450W and 34UM95. The 34UC97 is the curved version of the 34UM95.[14] The latter one features a TV tuner and is marketed as a Television Set. Other monitor manufacturers, such as Asus, Dell,[15] NEC and AOC, have since followed suit.

At the CES 2014, LG presented the 105UC9,[16] a 105-inch curved LCD TV with a 5120×2160p panel, one of the first two UltraHD 21:9 screens.


Also at CES 2014, Samsung presented a 105-inch curved LCD TV[17] with 5120×2160p as well, the other first UltraHD 21:9 screen.

Front projection

Besides projectors outfitted with anamorphic lenses, which optically scale 1920×1080p to a 21:9 aspect ratio, Digital Projection,[18] Projection Design[19] and Avielo[20] have released projectors that utilise 2560x1080 pixels of a 2560×1440 DLP chip with a spherical lens.


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