The video aspect ratio probably isn’t the first thing you think about when uploading your video online — but it should be! Getting the aspect ratio of your video right will bring the quality of your video’s image up to a high standard. And when viewers have countless video choices online today, you can’t afford to sacrifice quality, especially not for something as simple as the video aspect ratio.

The video aspect ratio is important, but what is it? How is it related to video resolution, and which aspect ratios should you use for uploading videos online? In this guide, we’ll cover everything you need to know about aspect ratios for your online videos and live streams.

👀 What is a video aspect ratio?

The video aspect ratio is a ratio, like 1:1 or 1:2, that determines the size and quality of your video’s image. The first number in the ratio is the width, and the second number is the height. Both the width and height are measured in pixels.

A common ratio for online video is 16:9. But an image 16 pixels by 9 pixels would be too small to see, so we use an image that’s 1920 pixels by 1080 pixels instead. Ratios may also be written as decimals, so 4:3 would be 1.33. The video aspect ratio is often determined by the device you’re viewing the image on.

Quick history lesson in video formatting

Aspect ratios go back to the beginning of film in the early twentieth century. The first aspect ratio ever used was developed with 35mm film and was the 4:3 aspect ratio. 4:3 was used until around the 1950s, when the widescreen “cinemascope” aspect ratio (2.35) took over. Aside from widescreen films at cinemas, 4:3 was the standard until the 1980s, with the rise of digital video. Around that time, the 16:9 ratio, which is directly between 4:3 and widescreen 2.35, was born. The 16:9 ratio has become the standard aspect ratio for flatscreen TVs and online video.

🤔 What is video resolution?

Now that you know what a video aspect ratio is, you need to understand video resolution and how the two fit together. Images are full of little squares, or pixels, placed side by side. The resolution is the number of pixels that make up the image on the screen, usually measured in PPI (pixels per inch). The higher your resolution, the more pixels you have per square inch. The more pixels you have per square inch, the higher the quality of your image.

The video aspect ratio and resolution are closely related. You get the resolution by multiplying width by height, and you get the aspect ratio by dividing width by height. If we use two numbers to calculate resolution, why do you only see resolution written as one number, such as 1080p? 1080 refers to the number of horizontal pixels in the image, or the height. We usually use the height (the second number) when talking about resolution, so 720p would indicate an image has 720 horizontal pixels, and 4K would be an image with approximately 4,000 horizontal pixels (3,840 exactly).

It’s worth noting that almost all digital screens use a 16:9 aspect ratio; only the resolution changes. The width and the height of the digital image is always 16:9, but the number of pixels per square inch increases as your resolution gets higher. Typically, the resolution of an image or video determines its aspect ratio. For example, 1080 looks best in a 16:9 aspect ratio. It doesn’t work the other way around, though, as the aspect ratio doesn’t affect your choice of resolution.

Using a higher resolution is almost always to your benefit — a higher resolution means a better-quality image. But there are times when a lower resolution is better, like if you need a smaller file size for your video or if you’re multistreaming to several platforms at once.

Resolutions explained

Here’s a quick run-down of resolutions and what they’re called:

  • Standard definition (SD): 480p (640 x 480)
  • High definition (HD): 720p (1280 x 720)
  • Full HD: 1080p (1920 x 1080)
  • 2K: 1440p (2560 x 1440)
  • 4K: 2160p (3840 x 2160) also UHD

💁‍♂️ What are the most common video aspect ratios?

We’ve mentioned a few video aspect ratios already, including 16:9 and 4:3. These video ratios aren’t your only options, though. Let’s go through the most common aspect ratios today and what they’re used for.

Aspect ratios explained


The 16:9 format is the standard aspect ratio for online videos, modern TVs, and movie theaters. 16:9 was developed to accommodate changing digital media trends, so it’s one of the most adaptable aspect ratios. It can support 1:1, 4:3, and 2.35 with the least amount of masking (the black bars you see on the sides or top and bottom of your video).


9:16 is the vertical version of 16:9. This aspect ratio became popular when you could start shooting video with a smartphone. Snapchat, Instagram Stories, Tik Tok, and Facebook Stories are the most common places you’ll find 9:16.


4:3 was the first aspect ratio used for film and was supported on box TVs and computer monitors until HD came along. 4:3 didn’t support higher resolutions very well, so 16:9 replaced it.


The perfect square ratio was used on TVs for a time, but now you’ll only find it on social media platforms such as Facebook and Instagram.


Ultra-widescreen films used to create a 360-degree effect use the 21:9 aspect ratio. It’s used in specialized theaters and some ultra-widescreen monitors and TVs.

Read later: Streaming setup for beginners 📍

🤓 Which video aspect ratios should you use for social media?

Not every social media platform uses the same video aspect ratio. In fact, different features on the same platform might require different aspect ratios.


The three places you can upload videos on Facebook are directly to the feed, in Facebook Stories, and on Facebook Live. Live videos should stick to the standard 16:9, while Stories should be the inverse, 9:16. The recommendation for videos uploaded to the feed is 1:1 or 4:5. 4:5 is a vertical/portrait aspect ratio that is popular on social media platforms.


Videos on Twitter can be in 16:9 or 1:1, but 16:9 looks better.

We used a 16:9 aspect ratio for the Friday Lives video clip in this Tweet.


You can add videos in four places on Instagram.

  1. Instagram feed: You can use either 16:9, 1:1, or 4:5, but 1:1 and 4:5 are recommended.
  2. IGTV: Most Instagram users don’t rotate their phones to watch a video on IGTV, so the vertical 9:16 is best.
  3. Instagram Live: Instagram Live should also be in 9:16.
  4. Instagram Stories: For Stories, you can either use the standard aspect ratio for digital, 16:9, or its opposite, 9:16. 1:1 and 4:5 also work. The best is usually 9:16, however.

Tik Tok

Tik Tok videos should be in either 9:16 or 1:1, but 9:16 is recommended. 1:1 videos won’t take up the entire screen.


On Snapchat, you can add a ten-second story or a long-form video ad. The story should be in 9:16, and the long-form ad can be 9:16 or 16:9.

Ultimately, your aspect ratio will depend on the type of video you’re uploading and where you’re publishing it. For desktop computers with widescreen monitors and flatscreen TVs, default to widescreen. For anything published on mobile, go with square (1:1) if you’re in doubt.

📹 Which video aspect ratios are good for live streaming?

For live streaming, the best video aspect ratio is usually 16:9, but it will depend on your platform. Both YouTube and Twitch have default aspect ratios of 16:9. If you use another aspect ratio, your stream will have black bars around it to conform.

How to change the aspect ratio and resolution in Restream Studio

You can stream in HD or Full HD when you multistream from the Restream Studio (you need a Pro plan for Full HD). You go to Settings → Quality and change the resolution from HD to Full HD. When you use Full HD with Restream, your aspect ratio should be 16:9 for the best quality. Restream is pretty flexible when it comes to resolution output for your live stream, since you’re not streaming directly from Restream to an audience, but from Restream to multiple platforms. Check out this guide for the best video settings for each major streaming platform.

Getting your video quality just right is a breeze with Restream, which duplicates your video quality exactly. Once you know the requirements on your chosen platforms, you can easily broadcast your stream to those platforms simultaneously.

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How to change the aspect ratio in OBS

You may find you need to change your aspect ratio to match the player of the platform you’re streaming to, if you want to avoid masking (the black bars). You may also want to change your output resolution to match the parameters of your platform. Luckily, the two are related.

If you’re using OBS 25 to live stream, one of the new features will show you your aspect ratio based on the resolution you’ve picked. It’s available in Settings → Video. You may have to restart OBS to see the changes.

🙌 Let’s wrap everything up

As you can see, video aspect ratios aren’t as complicated as they sound. Often, the devices and software you use to capture video will show you which aspect ratio your video is in. Changing it is also relatively easy. Just remember the purpose of your video or live stream and where it’s being uploaded, and you should have no problem choosing the best aspect ratio for your video.