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Aspect Ratios 101

September 11, 2013 | Comments

Ah, fine print. It's loaded with mumbo-jumbo and it's everywhere - even on your Blu-ray discs and DVDs. A few examples…

  • "Presented in a widescreen version which preserves the original aspect ratio of approx. 2.35:1"
  • "Widescreen 1.85:1"
  • "Widescreen Presentation (2.40:1)"

What do these numbers mean? What's "aspect ratio"?

Relax. Even if math was never your favorite subject, aspect ratio is nothing more than the shape of an image - its width in relation to its height. Let's look at a few examples related to movies and TV.

aspect ratio comparison graphic

When the U.S. switched to the all-digital high-definition television (HDTV) system a few years ago, we entered the age of widescreen TV. Prior to that, TV screens were squarish compared with the rectangular shape of today's HDTVs. Until HD came along, TV shows were shot in 4:3, which means the image was 4 units wide by 3 units tall or had "an aspect ratio of 4:3".

Movies made during Hollywood's Golden Age were also shot in 4:3 or 1.33:1, which is just a different way of saying 4:3 (4 / 3 = 1.33). (The format standardized by the Academy of Motion Pictures Arts and Sciences in the days of Clark Gable and Humphrey Bogart was actually 1:37:1, just slightly wider than 1.33:1.)

By the time the 1950s rolled around, Hollywood was looking for ways to compete with a new-fangled invention that was well on its way to becoming a fixture in living rooms across America: Television. To bolster box-office attendance, studios began shooting movies in widescreen and have been doing so ever since.

But unlike the movies that came before, which were shot in one standard format, aspect ratios have varied over the years from wide to ultra-wide.

Common Aspect Ratios

The most common aspect ratios used in theaters today are 1.85:1 and 2.35:1. The former befits a more intimate scale where people tend to be most prominent in the frame, which is why many dramas and comedies are shot in 1.85:1 (known as Academy Flat in the movie industry).

Significantly wider and more epic in scope, 2.35:1 is used for most of today's big-budget blockbusters because the panoramic presentation engages peripheral vision and makes viewers feel more immersed in the action.

The aspect ratio of today's HDTV screen is 16:9 or 1.77:1, which means that movies shot in either of these formats must be "letterboxed" with black bars above and below the image to preserve the film's original aspect ratio. While letterboxing is minimal with 1.85:1 programs, those black bars become prominent with 2.35:1 movies (see photo below).

Some TVs have a feature that lets you zoom in so the image fills the entire screen and the black bars disappear. Problem is, the sides of the image get cropped when you zoom in!

2.35:1 image on 16:9 screen
2.35:1 movie on 16:9 screen

In case you're wondering why the TV industry settled on a 16:9 (or 1.77:1) aspect ratio for modern widescreen televisions, it was an "equal pain" compromise for displaying 4:3 (or 1.33:1) content with bars on the side (pillarboxing) and 2.35:1 movies with bars above and below (letterboxing), and as noted above, movies shot in the popular 1.85:1 format can be displayed on widescreen TVs with minimal letterboxing.

To learn more about the ins and outs of home entertainment, consult a CEDIA professional. Click here for a list of CEDIA-member home technology professional companies in your area.