How to Export a Smaller File From iMovie on Mac

Open File > Share > File. The dialog has a handful of menus, and three of them decide how large the file is.

The dialog shows an estimated file size and updates it when you change a menu. Use that number as a guide while you pick settings, rather than guessing. Treat it as an estimate, not a promise.

More than anything else. iMovie’s own sizes vary by project and we did not run the iMovie interface, so we measured the same idea with Apple’s export presets on a command line. One 8-second 3840 × 2160 test clip went through each preset:

The clip is synthetic test footage, so the ratios are a direction, not a prediction for your project. The pattern is reliable, though: each step down in resolution cuts the pixel count and the file with it. Most videos shared by message, email or social platforms look fine at 1080p, and often at 720p. For the full set of resolution options, see how to change video resolution on a Mac.

Use Medium or High for anything you will upload or send. The Best (ProRes) option writes a very large file that is made for further editing, not for sharing, and it is only worth choosing when the next stop is another editing app. Low is the smallest file, with visible softness on detailed scenes.

A good order to try: set the Resolution first, check the estimated size, and only then lower Quality one step at a time. Resolution gives the larger saving for the smaller visible cost on most footage.

For the Low, Medium and High settings, iMovie saves a standard video file that plays on phones, TVs and in browsers. Apple’s Share dialog can also create a ProRes file when you pick Best, which is a different, much larger format. If a website insists on a specific extension, check the saved file name and, if needed, convert it. We cover that in how to convert MOV to MP4 on a Mac.

Duration and content both drive size, so edit before you export. Trim dead air at the start and end of each clip. Cut repeated takes. Delete clips you hid under others. A shorter movie is smaller than a longer one at the same settings, because the encoder has less footage to write.

Busy footage costs more bytes than calm footage. Handheld shots, water, confetti and fast pans take more data per second than a tripod shot of a person talking. If a project is mostly the second kind, you can often use a lower Quality setting without noticing.

Frame rate is another quiet factor. Footage shot at 60 frames per second carries twice the frames of 30 fps footage, and the export will be larger for it. If you shot at a high frame rate only out of habit, setting the project to a lower rate before you export can help. Check the project settings in your version of iMovie, because the controls differ between releases.

Use the Share dialog’s estimated size as feedback. Change one menu, read the number, then change the next. That way you learn which setting moves the file the most on your own project, which is more useful than any general rule.

Yes. In the same File > Share > File dialog, the Format menu has an Audio Only choice. This is the quick route when you only need the soundtrack of a recording, and the file is tiny compared with video. If you want the opposite, a silent video, see how to remove audio from a video on a Mac.

For podcast and music exports, the bitrate matters more than resolution, since there is no picture. Our audio bitrate guide explains what the numbers mean and where the quality starts to fall off.

Three common reasons. First, the project is long: file size grows with duration, so cut anything you do not need before you export. Second, the source is 4K or high frame rate and Resolution is still set to match it. Third, Quality is set to Best, which uses ProRes.

If you have already exported and the file is too big, do not re-edit the project. Run the exported file through a compressor. It is usually faster than a new iMovie render, and you keep the first export as your master. The guide to reducing video file size on a Mac covers the options. For a quick comparison of codecs, read H.265 vs H.264.

ffmpeg -i imovie-export.mp4 -vf scale=-2:720 -crf 26 smaller.mp4

This ffmpeg command is a free way to re-compress at 720p. We use the same idea in the measurements above, though we did not feed it an iMovie file.

If you are exporting one movie, stay inside iMovie. Lowering Resolution and Quality in the Share dialog is free, and iMovie already shows an estimated size. You do not need another app for a single export.

Smol earns its $29 (once, one Mac) after the export, when you have several finished movies or a folder of mixed clips to shrink. Drag them in, keep or reduce the resolution, choose H.265 or H.264 and a quality, and get a copy beside each original. Nothing is uploaded, and there is a Finder right-click action. Our compress video on Mac guide compares it with the free methods, and the best video compressor for Mac roundup covers alternatives. Or buy Smol.