The aspect ratio refers to the ratio between the height and width of a video, and it determines how the video looks on various players. For social media shares, different platforms require video with different ratios. For instance,for YouTube, the commonly used aspect ratio is 16:9, which is a standard for almost all videos. However, for TikTok or Instagram Reel, the required aspect ratio is 9:16.
The original aspect ratio of the video depends on the default Settings of the recording device. So if want to post your video to social media platform that ask for a specific ratio, you may need to change your video aspect.
You will learn in this article how to change video aspect ratio in iMovie.
Before We Begin…
Before we drive into how to change video aspect ratio in iMovie, please note that although the iMovie app comes with many great editing features, including adding text, adding music, cropping a video, splitting a video, etc., it is far from the perfect tool to change video aspect.
iMovie 10 or later versions only have widescreen (or 16:9) aspect ratio. You can crop/frame the video in iMovie to change the video size, but iMovie will insert black borders to make your video fill the screen of 16:9. If you want to use aspect ratios of 1:1, 9:16 or 21:9, then iMovie is not the proper tool to use in those instances.
Content:
Part 1: Best Way to Change Video Aspect Ratio to More Than 16:9
As we said before, iMovie is far from the perfect tool for changing the aspect ratio. When you change a video's aspect ratio in iMovie using the crop feature, it auto-adds pillarbox (black bars placed on the sides) or letterbox (black bars above and below) to your video to keep your video in the fixed aspect ratio at 16:9.
So we want to introduce a free online iMovie alternative, FlexClip, to change video aspect ratio and make your iMovie video in the ratio of 9:16 and more.
FlexClip is a powerful online video editor offering rich editing tools to help you make a stunning video. It can easily help you change the aspect ratio to 16:9, 4:5, 1:1, 21:9, and 9:16 in a few clicks.
How to Change Aspect Ratio with iMovie Alternative - FlexClip

Upload Your Video to FlexClip

Change Video Aspect Ratio with FlexClip
While you're in the editor, you can use FlexClip's tools to make any other edits you'd like to your video:
- Add & edit text animation to the video;
- Add transition effects, filters to the video;
- Add watermark, overlays & voice over;
- Split, trim, and rotate the video;
Also, you can make a stunning video with FlexClip's pre-made video templates:



Part 2: How to Change Aspect Ratio in iMovie on iPhone/iPad
Frankly speaking, the video aspect ratio conversion option isn't available at the moment in iMovie on the iPhone/iPad. But here is a workaround to help you change the video aspect ratio in iMovie on iPhone/iPad - Crop.

Import Video to iMovie on iPhone

Change Aspect Ratio in iMovie on iPhone
Part 3: How to Change Aspect Ratio in iMovie on Mac
It takes only a few steps to change the iMovie aspect ratio in old versions on Mac, simply go to "File > Project Properties > Aspect Ratio", and change the aspect ratio to 16:9 or 4:3.

Change Aspect Ratio in iMovie Old Version
However, Apple has already canceled the Aspect Ratio option in iMovie 10 (and later )Project Properties. The only workable way to change the video aspect ratio in iMovie on Mac is to enable the crop feature, but the aspect ratio is fixed at 16:9.

Change Aspect Ratio in iMovie on Mac
The Bottom Line
That's all for how to change the aspect ratio in iMovie and the best iMovie alternative to change the video aspect ratio freely - change aspect ratio online with FlexClip's online video editor. By the way, FlexClip is a powerful video editor/maker that helps you create stunning videos with great ease. Try it FREE!
