How to Change Output Aspect Ratio in OBS Recording Software

OBS (Open Broadcaster Software) is a popular open-source software for video recording and live streaming. One important setting in OBS is the output aspect ratio, which determines how the final video will be displayed on screens with different aspect ratios.

What is Aspect Ratio?

The aspect ratio refers to the proportional relationship between the width and height of an image or video. Some common aspect ratios are:

  • 16:9 – The standard widescreen aspect ratio used for HD TVs and computer monitors.
  • 4:3 – The standard fullscreen aspect ratio used in older TVs and standard definition video.
  • 21:9 – An ultrawide or cinematic widescreen aspect ratio.
  • 9:16 – A tall or portrait aspect ratio often used for mobile content.

Why Aspect Ratio Matters

The output aspect ratio setting in OBS is important because it determines how your recorded video will look when viewed on screens with different aspect ratios.

For example, if you record 16:9 video but a viewer watches it on a 4:3 display, they will see black bars on the top and bottom. Similarly, 16:9 video watched on a wide 21:9 display may have black bars on the sides.

By properly setting the output aspect ratio in OBS, you can create videos optimized for your target viewing platforms and prevent unwanted black bars.

How to Change Aspect Ratio in OBS

Changing the output aspect ratio in OBS is simple:

  1. Open OBS and click Settings > Video
  2. Under Base (Canvas) Resolution, select the aspect ratio you want from the dropdown menu. Some common options are:
  • 16:9
  • 4:3
  • 21:9
  • 9:16
  1. Under Output (Scaled) Resolution, select a resolution to match your selected aspect ratio. For example:
  • For 16:9, use 1920 x 1080
  • For 4:3, use 1280 x 720
  • For 21:9, use 2560 x 1080
  1. Click Apply to save the settings.

Now your recordings will match your selected output aspect ratio instead of your monitor’s native aspect ratio.

Advanced Aspect Ratio Tips

Here are some additional tips for working with aspect ratios in OBS:

  • For non-standard aspect ratios like 21:9, you may need to enter a custom resolution.
  • Match your canvas resolution and output resolution to prevent scaling issues.
  • For mobile content, use 9:16 aspect ratio rather than cropping 16:9 video.
  • Place background images/color in unused areas when letterboxing to avoid black bars.
  • Use the “Transform” tool on sources to stretch/crop content to fit non-native aspect ratios.
  • Create separate OBS scenes or profiles for projects with different aspect ratio needs.

Aspect Ratio Considerations

When selecting an output aspect ratio, keep the following in mind:

  • What is the primary viewer platform (YouTube, Twitch, etc)? Use their recommended aspect ratio.
  • Does all my source content match this aspect ratio? If not, plan to crop/scale.
  • Does my recording canvas resolution match my output resolution? This prevents scaling.
  • Will unused areas of the frame be filled or letterboxed? Plan backgrounds accordingly.

By properly configuring the output aspect ratio and planning ahead, you can create professional, polished-looking videos in OBS optimized for your target viewing platforms.

Frequently Asked Questions

Q: Why do I see black bars when viewing 16:9 video full screen on a 4:3 display?

A: This is because a 16:9 video is wider than a 4:3 display. The black bars are “letterboxing” to fill the extra space on the top and bottom. To avoid this, create videos in a 4:3 aspect ratio instead of 16:9.

Q: Can I convert a 16:9 video into 21:9 after recording?

A: Not easily. To create 21:9 video, you need to record that aspect ratio directly in OBS. The best way is to set 21:9 output resolution before recording.

Q: How can I get rid of black bars when watching 21:9 video full screen on a 16:9 display?

A: The black bars on the sides cannot be removed unless you crop the 21:9 video into 16:9. This will cut off content on the sides. There is no way to display 21:9 full screen on a 16:9 display without letterboxing.

Q: Why do my game recordings have black bars even though I set the output aspect ratio correctly?

A: Some games have their own internal aspect ratios separate from your display or OBS settings. You may need to adjust options in the game itself to stretch or crop it to fill the desired OBS output resolution.


Configuring the best output aspect ratio takes a bit of planning, but allows you to create videos optimized for your target platforms. Match your canvas, output resolution, and aspect ratio in OBS to prevent scaling or black bars. Test on sample viewers to fine-tune, and use tools like cropping/transforms to work with mixed aspect ratio sources. With the right settings, your recordings will look clean, professional and ready to share!