Full glossary

Aspect ratio

What is aspect ratio?

Aspect ratio refers to the ratio of the width and height dimensions of a video. You can calculate the ratio by dividing the width and height by the greatest common divisor of both.

For a video that is 1920 pixels wide and 1080 pixels in height, the greatest common divisor is 120, resulting in an aspect ratio of 16:9.

The two most common aspect ratios for video are 4:3 (e.g. 640x480) and 16:9 (1920x1080 or 1080p). With vertical video, popular for mobile device recording, the common aspect ratio numbers get reversed and 16:9 becomes 9:16.

The square aspect ratio, 1:1, is also becoming popular because of social sites like Instagram that allow square video as an option.

What is the history of the aspect ratio?

When film was first starting out, everything was shot in 4:3. This was the standard for motion pictures, so it was easy to create everything like this. However eventually, people began experimenting with different aspect ratios, especially wider ones, which could help to create a more immersive experience for film goers. As it turns out, wider aspect ratios do a better job of mimicing how we see the world around us. To be able to stretch films wider and wider, film creators originally used anamorphic lenses. These lenses distorted captured images vertically, allowing them to be stretched out later and look 'right' on wide screens. These lenses are still used today.

What are the most popular aspect ratios?

The most commonly used aspect ratios today are:

4:3 - It's what film started out on, but today it's more likely to be used for television and computer screens.

16:9 - Most cameras shoot with this aspect ratio, but this is more likely to be used for TV than any other medium.

1.85:1 - This is slightly wider and shorter in height than 16:9. It's used for television, but it's used for TV shows that are going for a more cinematic look-- thus the slight additional width and smaller height. There is a slight letterbox (band of black at top and bottom of video) on video shot in this aspect ratio.

2.35:1 and 2.39:1 - These are used for films that are going to appear on the big screen. These aspect ratios always give a more immersive, filmlike quality to whatever's being shot. They're great for the cinema, but because they result in a bigger letterbox, people don't like this aspect ratio as often if they're watching something on TV.

Why do aspect ratios matter?

Aspect ratios evoke different kinds of feelings in viewers. Even an untrained viewer will feel different when they see a really wide, cinematic shot vs. a smaller, narrower television type shot. The wider aspect ratio can be used to create more dramatic landscapes while narrower shots can be used to give a more everyday feel. The psychological effects of aspect ratio on a story's theme, narrative and dramatic tension is a popular topic of debate.

Aspect ratio and

At, because content is transcoded to [HLS] so that it can easily be streamed across the web, the aspect ratio by default is 16:9.