16:9 Was Not Chosen Because It Looks Best. It Was Chosen Because It Wastes the Least Screen Area.
16:9 Was Not Chosen Because It Looks Best. It Was Chosen Because It Wastes the Least Screen Area.
The 16:9 aspect ratio did not emerge because it is the most visually compelling proportion for the human eye. It emerged because a mathematician in 1984 calculated which ratio would waste the least screen area when displaying content made in every other format then in use.
Kerns Powers, a member of the SMPTE Working Group on High-Definition Electronic Production, was confronting a practical problem: cinema used several different widescreen formats, television had used 4:3 for fifty years, and a new HDTV standard needed to work reasonably well for both. Powers' method was geometric rather than algebraic. He cut out rectangles with equal areas, each shaped to match a commonly used aspect ratio, then overlapped them at their center points. Every rectangle fell within an outer rectangle measuring 1.77:1, and every rectangle covered a smaller inner rectangle of the same proportion. That ratio, 1.77:1, is essentially 16:9. It is the geometric mean of the extreme ratios in common use at the time.
The standard was adopted by SMPTE in the early 1990s and has since appeared on essentially every laptop, monitor, smartphone, and television manufactured. Every time you watch a video, open a laptop, or frame a photograph for social media, you are using a ratio that came from an engineer's attempt to minimize compromise.
The 4:3 ratio that 16:9 was designed to replace had its own historical origin that most people do not know.
Early cinema shot on 35mm film stock established proportions based on the physical width of the film and the height of the frame. When synchronized sound arrived in the late 1920s, it required allocating a narrow strip along one side of the 35mm frame for the optical audio track. This changed the shape of the remaining picture area. The Academy of Motion Picture Arts and Sciences standardized the resulting proportions as the Academy ratio in 1932: 1.375:1, or approximately 4:3. Television engineers in the 1940s adopted these proportions when designing the first broadcast systems, because matching the cinema ratio made sense for a medium expected to show films.
The 4:3 ratio dominated television and early computer monitors for fifty years. CRT monitors were manufactured to this shape because it matched the broadcast signal. The shape felt natural to audiences and users because it was the only shape they had ever seen.
By 1984, cinema had fragmented into several competing widescreen ratios, each serving different production contexts.
The American "flat" format used a 1.85:1 ratio, achieved by masking the top and bottom of the Academy frame. European films used 1.66:1, slightly narrower. Anamorphic widescreen, using CinemaScope and later Panavision lenses, used approximately 2.35:1 to 2.39:1, nearly twice as wide as tall. IMAX used ratios closer to the original Academy frame, around 1.43:1.
Powers evaluated these formats along with 4:3 television. The popular choices in 1984 included 4:3, 5:3 (1.67:1), 1.85:1, and 2.35:1. Displaying any of these on a screen of a different ratio requires either black bars (letterboxing for wider content, pillarboxing for narrower content), cropping, or distortion. Powers' geometric mean approach identified 16:9 as the ratio that minimized the average area of black bars across all these formats when displayed on the same screen.
This is why 16:9 content sometimes still has black bars when shown in certain cinema formats. A 2.35:1 film displayed on a 16:9 screen still has letterboxing above and below. But the bars are narrower than they would be on a 4:3 screen, and the image is wider than it would appear on a 4:3 display.
Aspect ratio problems appear in three forms, and each requires a different calculation approach.
Reducing a ratio to its simplest form requires finding the greatest common divisor of the two dimensions and dividing both by it. The ratio 1920:1080 shares a GCD of 120. Dividing both by 120 gives 16:9. The ratio 2560:1440 shares a GCD of 160, giving 16:9 again. The ratio 1280:720 gives 16:9 through GCD of 80. These are all the same underlying proportion.
Scaling both dimensions while preserving a ratio requires multiplying both values by the same factor. If a 16:9 design at 1920x1080 pixels needs to scale to a 2560-pixel width, the height is found by (1080 / 1920) x 2560 = 1440. Any multiplication or division applied to one dimension must be applied to the other identically.
Finding one missing dimension from the other requires setting up a proportion. If you know the ratio is 16:9 and the width is 640, the height is (9 / 16) x 640 = 360. This type of calculation appears constantly in video production, web design, and print layout when one dimension is constrained and the other must be calculated.
Different platforms have established their own aspect ratio conventions based on how their interfaces present content, and working with images or video across platforms requires knowing these conventions.
YouTube and most streaming platforms use 16:9 as the primary format for horizontal video. Content shot at 16:9 fills the player without black bars. Content shot at other ratios will have bars or be cropped depending on the platform's handling.
Instagram has supported multiple ratios. The feed accepts square (1:1), portrait (4:5), and landscape (1.91:1) images, with 4:5 portrait giving the most screen area in the feed. Stories and Reels use 9:16, which is 16:9 rotated: a full-screen vertical format. TikTok uses 9:16. YouTube Shorts uses 9:16. The shift toward vertical video has made 9:16 as important as 16:9 for creators producing content for multiple platforms.
Print and photography have different conventions. The standard 3:2 ratio used by 35mm film and most DSLR cameras originates from the 35mm film frame, which measured 36x24 millimeters. This ratio differs from the 4:3 used by many smartphone cameras and from the 16:9 used by video. Converting between these ratios for print, social media, and video use requires calculating which parts of the image will be cropped in each context.
The 16:9 ratio has a decimal value of approximately 1.778. The golden ratio, often cited as an aesthetically ideal proportion, has a value of approximately 1.618. These are different numbers, and 16:9 was not chosen for aesthetic reasons.
The golden ratio, denoted by the Greek letter phi, appears in classical architecture, Renaissance painting composition, and certain natural patterns. Designers and architects have used it as a proportion guide for centuries. For photographic composition and graphic design, ratios close to the golden ratio (3:2 at 1.5, 4:3 at 1.333) are often used as composition guides.
The practical display standard of 16:9 has no relationship to these classical proportions. It is an engineering compromise that minimizes information loss across legacy formats. The reason the golden ratio does not dominate screen design is that screens are manufactured to engineering standards set by committee, not aesthetic ideals.
Conclusion
Kerns Powers' 1984 geometric mean calculation produced a standard that billions of people interact with daily without knowing its origin. The 16:9 ratio on every screen you own came from an engineer trying to minimize waste across five incompatible format systems, not from a decision that this shape was the most beautiful.
An aspect ratio calculator simplifies the three common ratio calculations: reducing ratios to simplest form, scaling dimensions proportionally, and finding a missing dimension from a known ratio and one dimension. ToolHQ's aspect ratio calculator handles all three without manual arithmetic.
Frequently Asked Questions
Why is 16:9 the standard aspect ratio for screens?
In 1984, SMPTE engineer Kerns Powers determined that 16:9 is the geometric mean of all common film and TV aspect ratios. Adopting it as the HDTV standard minimized wasted screen area across all existing content formats.
What is the difference between 16:9 and 4:3?
16:9 (widescreen) is significantly wider relative to its height than 4:3 (nearly square). Modern TVs, monitors, and smartphones use 16:9. Older TVs, early computer monitors, and some cameras used 4:3.
How do you calculate a missing dimension while maintaining aspect ratio?
Divide the known dimension by the ratio component for that dimension, then multiply by the ratio component for the unknown dimension. For 16:9, if width is 1280, height equals (1280 / 16) x 9 = 720.