21:9 aspect ratio
"21:9" is a consumer electronics marketing term to describe the ultrawide aspect ratio of 64:27, designed to show films recorded in CinemaScope and equivalent modern anamorphic formats. The main benefit of this screen aspect ratio is a constant display height when displaying other content with a lesser aspect ratio.
The 64:27 aspect ratio of "21:9" is an 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 and optical anamorphic lenses to use an easily implementable 4:3 scaling factor.
SDTV
HDTV
"21:9"
The term "21:9" was chosen as a marketing term, first used by Philips in January 2009. Due to its common denominator, 21:9 is more relatable to 16:9, the aspect ratio of regular HDTVs, rather than the more accurate 64:27. If it actually were 21:9, the fraction could also be expressed in the reduced form as 7:3, relating to the 4:3 of standard-definition TVs.
Consumer TVs with this aspect ratio were manufactured mainly from 2010 to 2017. Due to it causing pillarboxing with standard 16:9 content, and the resulting low consumer acceptance, this screen format has rarely been used since then.
It is still prevalent in projection systems, using anamorphic lenses, and supported by a number of consumer electronics devices, including Blu-ray players and video scalers.
It is also used in computer monitors, where the term "21:9" can also represent aspect ratios of 43:18 and 12:5 in addition to 64:27. The wider screen provides advantages in multitasking as well as a more immersive gaming experience, and even wider screens with aspect ratios such as 32:9 are available. 21:9 phones also exist.
Constant image height
With content of different aspect ratios, adjustments have to be made when showing such content on a display with a fixed aspect ratio. To avoid loss of content or distortions, horizontal or vertical bars of a uniform color, usually black to make them less noticeable, are added to adjust the image. With the black bars being unnoticed, this has the effect of a changing image size when switching content aspect ratios.A 21:9 display is able to present all content up to 'Scope aspect ratios at equal height, with changing vertical bars to the left and right of the image. Note how the large center circle, representing the main image area, remains at a constant size on the 21:9 display, while it changes on the other two depending on the aspect ratio of the content.
| 4:3 content | 16:9 content | 21:9 content | |
| 4:3 TV | |||
| 16:9 TV | |||
| 21:9 TV |
Uses
Cinema
The "21:9" digital format's aspect ratio of 64:27 is positioned between the classical CinemaScope aspect ratio and the aspect ratio of modern anamorphic cinematic content, matching both with only a slight deviation. Thus, 21:9 screens allow watching most films with minimal letterboxing or pillarboxing.Video games
Most modern 3D video games support 21:9 monitors, allowing for a wider field of view and increased immersion. In certain multiplayer games the increased horizontal FOV can give the player with the ultrawide monitor a competitive advantage, revealing information not available to an average player, while in other games the vertical FOV is decreased instead. While not as common, various 2D games also support 21:9 monitors, such as Hollow Knight: Silksong.Standardization
HDMI
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, CTA 861-F:- 1280×720p, anamorphic pixel aspect ratio of 4:3
- 1680×720p, near-square pixel aspect ratio of 64:63
- 1920×1080p, anamorphic pixel aspect ratio of 4:3
- 2560×1080p, square pixel aspect ratio
- 3840×2160p, anamorphic pixel aspect ratio of 4:3
- 5120×2160p, square pixel aspect ratio
- 7680×4320p, anamorphic pixel aspect ratio of 4:3
- 10240×4320p, square pixel aspect ratio
- 11520×6480p, anamorphic pixel aspect ratio of 4:3
- 15360×6480p, square pixel aspect ratio
- 15360×8640p, anamorphic pixel aspect ratio of 4:3
- 20480×8640p, square pixel aspect ratio
Blu-ray
An effort by Panamorph in 2012 to add support for anamorphic video in a 21:9 aspect ratio to the Full HD, 3-D and Ultra HD Blu-ray specifications was unsuccessful and ultimately did not get included into the final specification. Blu-ray Discs include the letterbox bars in the encoded 16:9 picture, which means widescreen movies, without additional processing, will be shown with black bars on top and bottom. The company Folded Space, also initiated by Panamorph, was working on a proprietary solution, MFE, to put anamorphic 21:9 video onto Blu-rays in a way compatible with standard players.Content and source devices
Blu-ray
Some Blu-ray players, e.g., the Oppo BDP-203/205, or Philips BDP3200/12 and BDP9100/05, did support a 21:9 output mode. In this mode, the player has the capability to trim the letterbox bars and extract the 21:9 center portion of the movie content of a letterboxed disc, upscale it vertically, and scale and re-arrange the 16:9 menus and subtitles for that 21:9 anamorphic upscale so that no user interface elements are trimmed off with the bars.| Video and Subtitles stored on a Blu-ray | 21:9 content extracted and upscaled, with subtitles shifted out of the cropped letterbox bars | Anamorphic frame shown stretched on 21:9 display, now correct and with all subtitles |
Streaming services
Video streaming and download services use a proprietary technical infrastructure, and are not confined to the same strict rules about frame aspect ratios as standardized distribution services. They therefore often encode content as just the active frame, without any aspect ratio adjustment bars. Movies with a 2.39:1 aspect ratio are a natural match for 21:9 output video timings, as long as the streaming clients support such video modes, and even content with other wide aspect ratios such as 2.00:1 and 2.20:1 are inherently maximizing the use of the output frame on such systems.Amazon Prime Video, YouTube, and Netflix support ultrawide movies/videos, while Tubi TV, Disney+, and Hulu still do not.
Apple TV
, in September 2024, announced upcoming support for 21:9 with tvOS 18 for the Apple TV streaming box: "Available later this year, tvOS 18 brings 21:9 support for playing movies and shows on projectors, "Apple TV 4K with tvOS 18.3 supports the new feature, with the aspect ratio choices 16:9, 21:9, 2.37:1, 2.39:1, 2.40:1, DCI 4K, and 32:9. This provides separate selections for 21:9 and 2.37:1. The exact scale ratios are still to be confirmed as of November 2024.
Display 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. Philips' "Cinema 21:9" TV eliminates the black bars by scaling the 1920 horizontal resolution to its full width of 2560 and the 800+ pixels of CinemaScope images 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. Despite the intention being to fill the screen with a non-letterboxed image, the zoom mode can result in some cropping at the edges. 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.Philips
The Philips "Cinema 21:9" TV was the first LCD television of this aspect ratio. 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 screen sizes of 50 and 58 inches.Early reviews claimed that it was "one of the coolest TVs" to enter the market for some time. 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, titled Carousel, went on to win the most prestigious award in the advertising industry, the Grand Prix at the Cannes Lions International Advertising Festival.
In 2012, Philips stopped production on all its 21:9 televisions due to lack of demand.
Vizio
followed Philips in 2011 with their own Cinema TVs with identical resolution, similarly marketed as "21:9" in the United States.The 58-inch TV with a panel resolution of 2560×1080 was sold in 2012 and 2013, but was then discontinued. A planned 50-inch model never made it to market.
LG
has a number of monitors with panel resolutions of 2560×1080, 3440×1440, 3840×1600 and 5120×2160, the latter being advertised by LG as '5K2K' with a 21:9 aspect ratio.Other monitor manufacturers, such as Acer, AOC, Asus, BenQ, Dell, Gigabyte, HP, Iiyama, Lenovo, MSI, NEC, Philips, Samsung and Viewsonic, have since followed suit.
At the CES 2014, LG presented the 105UC9, a 105-inch curved LCD TV with a 5120×2160 panel, one of the first two ultrawide 5K screens. LG started selling the TV in early 2015 for approx. $100,000 in the U.S., the only ultrawide TV in the market that year.