Understanding Aspect Ratio: A Quick Guide to Online Video FormatsShawn Forno 06.28.2017
Aspect ratios might seem confusing—4:3, 16:9, 2.76, 1.78, 2.35—all that math starts to blur into technical gobbledygook pretty quickly. How do you know which aspect ratio is right for your video? How do you decide between all the different resolutions? What is the default aspect ratio on YouTube and Vimeo? When it comes to video aspect ratios, there are a lot of technical questions. Luckily, choosing the right aspect ratio for your video is really simple once you understand a few things about video formatting.
So let’s dive into a quick history of aspect ratios, how they got to be the way they are, some common formatting choice for online platforms, and how to choose the aspect ratio that looks best for your video. Video aspect ratios are more interesting than you think—I promise.
What is an Aspect Ratio?
As film historian and aspect ratio super geek, John Hess from FilmmakerIQ puts it, “The aspect ratio is a ratio of the width of an image to the height.” Exciting stuff, right? Basically, what Hess means is that the aspect ratio determines the quality and size of your video, whether it’s on a movie screen, a phone, or your HD tv. And aside from a few widescreen exceptions (more on that in a second), there are basically two options when it comes to aspect ratios—4:3 (also written as 1.33) and 16:9 (also called 1.78).
But what’s the difference between the two, and why are they the industry standards?
Aspect Ratio History: Thomas Edison and the Kinetoscope
If you’re grew up watching a classic, tube television (basically any television set before flat screens) you’re familiar with the “Standard” 4:3 aspect ratio. The 4:3 aspect ratio dominated basically all television production for 50 years, but this aspect ratio actually dates back to the birth of cinema and comes from the shape of the film strip itself.
When Eastman Kodak began mass-producing flexible film in the 1890’s, Thomas Edison used that film in his early film camera called the “Kinetoscope.” Edison’s staff photographer, William Dickson, was in charge of the project and he used the pliable 35mm film. Dickson was tasked with creating a standard image size on this brand new medium, so he used the holes on the side of the film as a gauge. He settled on counting off four perforations (those little holes on the side of film strips) to mark the height of each image (frame), and thus the 4:3 aspect ratio was born.
4:3 aspect ratio quickly became the standard of all silent films, officially becoming the motion picture standard in 1909. Dickson’s four perforation marker was practical, simple, and 35mm film was the only mass produced film on the market for decades. The holes on the side of 35mm film are still called “Edison perforations.” The 4:3 aspect ratio would remain unchanged until The Academy (yes, that Academy) adapted the 4:3 (1.33) ratio to accommodate printed soundtracks on film strips in 1937, and then only by a fraction (1.37). It wasn’t until the breakthrough of widescreen films in the 1950s that aspect ratios became the confusing landscape they are today.
Widescreen Aspect Ratios: Cinemascope and the Anamorphic Lens
Ever seen a film “adapted to television” that looks a little stretched or has those obscuring black lines at the top and bottom? Welcome to widescreen aspect ratios. In the 1950’s widescreen travel films showed audiences a panoramic view for the first time—and they loved it. Productions like How the West Was Won (1962) changed the cinematic landscape in the 1950’s and 60’s—literally. Shot and projected on a special three-camera “Cinemarama” system this luscious widescreen film format floored audiences so much so that the standard 4:3 aspect ratio wasn’t enough to satisfy moviegoers anymore.
In 1953, 20th Century Fox developed a special anamorphic lens, called “Cinemascope,” that stretched traditional 4:3 35mm film aspect ratios (1.33) to a grand 2.35 aspect ratio by warping the image horizontally. Translation: this lens made 35mm film look wider. The results were spectacular. The only problem—resolution.
Aspect Ratio vs. Resolution: The Birth of HD
When you stretch a 4:3 (1.33) image to make it a widescreen image (2.35) you don’t just magically make the image bigger—you enhance the grain of the film as well. Think of this as blowing up an image to make it fit on your wall. You’ve made it larger, sure, but now you can see all the pixels. This is the major problem with widescreen aspect ratios like 2.35. Paramount tackled this resolution problem head on by creating not just a new aspect ratio (1.85), but a new way to shoot on film.
Instead of shooting on 35mm film vertically, Paramount turned the film sideways and shot each image horizontally, using eight Edison perforations as the width marker for each image. They then reprinted these images on vertical 35mm film for projectors and a new widescreen aspect ratio was born, with much higher image quality. The first use of this innovation was the classic White Christmas (1954) and The 10 Commandments (1956). Hitchcock was a huge fan of the 1.85 aspect ratio, and practically shot all his films this way.
Other film innovations like 70mm film allowed for truly widescreen HD productions in the 60’s and beyond, and ushered in the era of new industry standard widescreen HD aspect ratios like 2.20 (The Sound of Music) and 2.76 (Ben Hur). However, everything changed with the switch to digital media and HD tvs in the late 1980s.
The Most Common Aspect Ratios: 4:3 vs. 16:9
4:3 aspect ratio became the standard because cameras used 35mm film for decades. Innovations in the 1950’s changed things with new HD standards and a 2.35 aspect ratio. So where does the 16:9 (1.78) aspect ratio come from and why don’t online video platforms and HD screens use a higher aspect ratio?
The common adoption of the 16:9 aspect ratio, known as HD widescreen, is a direct compromise between 4:3 (1.33) standard and cinematic widescreen 2.35 aspect ratios. It’s literally the middle ground—mathematically—between the two most commonly used aspect ratios and was chosen as the standard for new HD tvs and digital screens in the late 80s for that exact reason.
Basically, the 16:9 aspect ratio works so well because you can crop 4:3 aspect ratio images with pillar boxes (vertical lines) and 2.35 aspect ratios with letter boxes (horizontal black lines) without warping or distorting the image. It works equally well both ways, and this quick fix made adapting film to digital screens a quick fix. The rise of higher resolution screens—720p, 1080p, and 4k—simply meant richer images in the 16:9 format, not a change to the way we view images on our devices and screens.
HD Widescreen Aspect Ratio: 480p, 480i, 720p, 1080i 1080p, 4K
It’s worth pointing out again that almost every single digital media resolution is based on the 16:9 aspect ratio. The only difference between all these formats is the resolution, not the aspect ratio. Think about the difference between aspect ratio and resolution like this—aspect ratio relates to the proportion of the canvas you’re painting on, resolution refers to the width of your paint brush.
The higher the number, the more brush strokes (pixels) per square inch, but no matter the size of your screen, the aspect ratio—16:9—is always a constant.
Online Video & Aspect Ratio: 16:9 and Beyond
“So what aspect ratio should I use when I upload my video to YouTube?” you ask.
Good question. 99% of the time, you’ll use the 16:9 aspect ratio when uploading your video online.
All online video platforms use 16:9 aspect ratios because designers in the late 80’s all agreed on this aspect ratio. Computer screens, phones, and tablets all conform to this standard. That’s why YouTube recommends uploading videos in 16:9 aspect ratio formats. You can use another aspect ratio, but YouTube will format your video into 16:9 by adding black letterboxes to make it conform to their standard resolution.
Vimeo also primarily uses 16:9 aspect ratio, but they offer filmmakers a few other options ranging from standard 4:3 ratio all the way up to 4K Stereoscopic 360 (2:1). However, 16:9 is still the majority aspect ratio, so unless you’re Tarantino, use 16:9.
Choosing an Aspect Ratio
Always use 16:9 aspect ratio when you upload your video to YouTube, Vimeo, or your own website. Getting the aspect ratio right is a boring detail, but it’s the little things that make a video great. Viewers will appreciate you playing by the rules.
Contact us today, and let us geek out and help you make your next video in 4:3, widescreen, or even VR.