How to Compress Videos in iMovie on Mac

In order to decrease the size of a video file, it must be compressed. This can be done in the final stage of video editing in iMovie. Simply click the “Share” button and choose “Export” File. From there, you can adjust the resolution, quality, and compression settings to meet your needs.

Hi, my name is Nancy, and I’ve been using iMovie to make videos for several years. One of the challenges of video editing is compressing video files to reduce their size without compromising quality. 

In this article, I will share some helpful tips on how to compress videos and answer some common questions related to this topic.

What Are the Best Settings to Compress a Video?

Reducing the size of a video file can make it easier to send to your friends and help speed up the process of uploading it to YouTube. 

I’ve compiled some useful information to help you get started. First, let’s examine the iMovie export settings and see how they impact a video file. 

  1. Resolution: The resolution is the size of a video frame measured by the number of pixels in width and height. For example, a 1080p resolution means that the video frame has 1920 pixels in width and 1080 pixels in height. While higher resolutions result in better video quality, they also require more storage space and processing power, which in turn results in larger file sizes and longer uploading times.
  1. Quality: In iMovie, the quality setting refers to the bitrate, which is measured in megabits per second (Mbps). The bitrate determines the amount of data used for each video frame. A higher bitrate results in better quality, but it also leads to larger file sizes. A lower bitrate produces lower quality, but it results in smaller file sizes.
  1. Compress: In this setting, there are two options to choose from, “Faster” and “Better Quality.” For longer videos, it’s recommended to choose the “Faster” option, while the “Best Quality” option is more suitable for videos with smaller file sizes. However, it’s important to note that neither option changes the overall file size in the end.

What are the optimal settings for compressing a video? Based on my experience, it is crucial to export a video in high quality while keeping a reasonable file size. While a smaller file size can reduce uploading times, no one wants to watch a pixelated, low-quality video. 

Below are my recommended export settings that reduce a file size without compromising on video quality.

I opted to export the video in 720p resolution, high quality, and compressed to the better quality option. As a result, the file size is only 25.9 MB, and it will be saved in the MP4 format.

How to Reduce the File Size of a Video in iMovie?

To export your movie, simply click on the “Share” button and select “Export File.” From there, you can choose the settings to save your file. Keep in mind that your choices for resolution, quality, and compression will all impact the file size. 

Here is an example of how to compress a video file to the smallest file size.

In the export settings, I have selected a 540p resolution, Low Quality and compressed to the Better Quality option. You can see that the estimated file size will be 5.5 MB and it will be saved in the MP4 file format. 

I have created a side-by-side comparison of two video files: one compressed to the smallest possible size, and the other saved in the highest quality. Upon inspecting the video information for both files, it’s clear that there is a significant difference in the file sizes.

The video compressed to the lowest quality settings has a file size of 14.8 MB, while the video compressed to a higher quality has a file size of 984.1 MB, which is almost 1 GB.

The video compressed to a smaller file size did experience a slight decrease in resolution quality because it was less clear and sharp. However, given that the original video was shot in 4K, the overall quality remained good. 

The only downside is that when this smaller file size is uploaded to YouTube, the maximum quality setting will only be 480p.


Here are some other questions related to compressing videos in iMovie on Mac.

Do Videos Need to Be Compressed?

If you’re planning to share the video online, it’s often a good idea to compress it to reduce the file size and make it easier to upload and share. There are plenty of free video compression programs available online that can help reduce the file size of your videos without compromising their quality.

Does Compressing a Video Affect Quality?

Yes, compressing a video can affect its quality. When you compress a video, you are essentially reducing the amount of data stored in the file by removing some of the details in the video. This can result in a loss of quality, especially if the compression is done at a high level. 

Why is My iMovie Video File So Big?

The size of an iMovie video file can be affected by several factors, including the length of the video, the quality of the video, and the format in which the video is saved.

Final Thoughts

Reducing the size of a video file can be a complex process that involves several technical factors. Adjusting the export settings in iMovie can result in a smaller file size with a decrease in quality or a larger file size with the best quality. It’s important to choose the export settings that best fit your needs and how you plan to share the video.

If you have any other questions about how to compress videos in iMovie, let us know in the comment below.

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