When your iMovie library is taking up space, it's almost always the footage you imported. iMovie keeps the clips you import inside its library, so a few hours of video can fill tens of gigabytes.
The part you can remove without losing anything is the render files: in iMovie, choose iMovie › Settings and click Delete next to Render Files.
Final Cut Pro has a bigger version of the same thing. Its libraries also hold render files, optimized media and proxy media, all made from your footage. Select a library and choose File › Delete Generated Library Files to remove them; Final Cut makes them again when it needs them.
Everything else in either library is your own work: clips, photos and the edits in your projects. To free that space, delete whole events you don't need inside the app, or move the library to an external drive with Apple's own steps.
Never open a library package in Finder to delete files from inside it. iMovie and Final Cut keep a database of every clip, and removing files behind their backs can damage the library. Every change goes through the app.
What's inside an iMovie library
Apple describes an iMovie library as holding your projects and all the media and data they use. It's one item in Finder, but it's a package: a folder macOS shows as a single file.
What does iMovie keep in the library?
| Part | What it is | Can it be made again? |
|---|---|---|
| Events | Clips and photos you imported, grouped by date | No, unless you have the originals |
| Projects | Your movies and trailers: the edits, titles and music | No |
| Render files | Previews iMovie makes to play effects smoothly | Yes, iMovie makes them again |
| Project media | Clips a project uses, shown above the Libraries list | Only from the original files |
The catalog's entry for iMovie libraries says it plainly: render files can be deleted in iMovie's settings, and everything else is your own media and edits.
Where is the iMovie library on a Mac?
By default, it's in the Movies folder in your home folder, named iMovie Library. In Finder, choose Go › Home, then open Movies. If it isn't there, Apple suggests searching for iMovie Library with Spotlight.
You can have more than one. File › Open Library › New creates another, anywhere you choose, and each one is a separate package with its own events and projects.
Why shouldn't you open the library in Finder?
Finder lets you look inside a package with Show Package Contents, and the video files are right there. Deleting them doesn't tell iMovie, which still lists the clips and can no longer play them, and projects that used them break.
So make every change in the app that owns the library. The catalog's Final Cut entry warns that changing files inside a library in Finder can damage it, and the same holds for iMovie.
How does Storage settings count it?
Storage settings has no iMovie category. Libraries in your home folder are counted with Documents, which Apple describes as files in your home folder that aren't in other categories, including videos your photo library doesn't manage.
Apple's guide says you can sort the files in Documents by Size in System Settings › General › Storage, so a large library stands out quickly. The post on finding large files on a Mac covers other ways to spot one.
What's inside a Final Cut Pro library
Final Cut Pro libraries work the same way, with more parts and more control over where each part lives.
Managed media and external media
Apple calls media you import into a library managed media: it's stored inside the library. Media can also stay outside, on any drive, and be linked to the library as external media. In the import window, Copy to library makes managed media, and Leave files in place links to files where they are.
That choice decides what deleting a library takes with it. Managed media goes with the library. External media stays where it is, and the library only points to it.
What are render, optimized, proxy and analysis files?
Apple groups them as generated media: files Final Cut creates in the background from your original media.
| Generated file | What it's for | Deleted by Delete Generated Files? |
|---|---|---|
| Render files | Smooth playback of effects, titles and transitions | Yes |
| Optimized media | Footage converted to Apple ProRes 422 for editing | Yes |
| Proxy media | Smaller ProRes 422 Proxy or HEVC copies | Yes |
| Analysis files | Results of color, audio and people analysis | No |
| Thumbnails and waveforms | Pictures of clips and sound in the browser | No |
Apple's guide says the Delete Generated Files commands delete render, optimized and proxy files only. Original media is never touched, which is why all three can be made again.
Where does each part live?
Each library has its own storage locations, set in its Library Properties inspector. Apple lists the defaults:
| What | Default location | Holds |
|---|---|---|
| Media | Inside the library | Imported, optimized, proxy and consolidated files |
| Cache | Inside the library | Render and analysis files, thumbnails, waveforms |
| Backups | The Movies folder | Copies of the library's database |
| Motion content | The Motion Templates folder in Movies | Effects and titles made in Motion |
Any of these can point to another drive. A library whose media and cache live elsewhere can be small, while its footage fills an external disk.
How do you see what a Final Cut library takes?
Select the library in the Libraries sidebar and choose File › Library Properties. Near the bottom, Storage Used for Media and Motion Content lists each drive with the original, optimized and proxy media on it. Apple's move guide says scrolling to Cache shows how much generated files take.
For the library's total, select it in Finder and choose File › Get Info, as Apple's storage article suggests. Remember that external media isn't included in that number.
Why your iMovie library is taking up so much space
Video is large, and both apps keep copies you may not know about. Here's where the space usually goes.
Footage adds up fast
Every clip you import from an iPhone, a camera or a folder is copied into an event. Recording in 4K or at high frame rates makes each minute larger. Apple doesn't publish typical library sizes, because they depend entirely on what you shoot.
In Final Cut Pro, optimized media adds a second copy of the footage. Apple's ProRes figures give a sense of scale: ProRes 422 targets about 147 Mbps at 1920 by 1080 and 29.97 frames a second, and ProRes 422 Proxy about 45 Mbps.
- Optimized media, ProRes 42266 GB
- Proxy media, ProRes 422 Proxy20 GB
Worked out from the target data rates in Apple's About Apple ProRes article, for 1920 by 1080 at 29.97 frames a second. Real files vary with frame size, frame rate and content.
So an hour of footage you optimized can mean the original plus about 66 GB more. Apple says proxy files take up considerably less storage space than optimized files, and improve editing performance too.
Deleting clips doesn't free space in iMovie
Apple's iMovie guide is clear: to free up storage space, you must delete an entire event. Deleting clips from an event doesn't free space, and pressing Delete on a clip only marks it as rejected.
That surprises many people who trim an event clip by clip and see no change. Move the clips you want to keep to another event, then delete the old event whole.
Deleting a project can leave its media behind
When you delete an iMovie project that contains media, Apple says a new event with the project's name appears in the library, holding that media. The project is gone, but its clips aren't, until you delete that event too.
Copies from older versions and other apps
When iMovie 10 updates projects and events from earlier versions, Apple says it copies them into a new library, and the originals stay usable in the older app. Both copies take space until you decide which to keep.
File › Send Movie To Final Cut Pro copies the project and its media into a Final Cut library. After sending, the same footage sits in both apps' libraries.
Updating also happens per drive. Apple says iMovie 10 creates a new library on each storage device that holds projects and events from older versions, so an old external drive can carry its own updated library beside the originals.
Copying projects between libraries
In Final Cut Pro, Apple says copying a project to another library doesn't copy its render, optimized or proxy files by default, because they can be made again quickly. Managed media used by the project does go with it, so two libraries can each hold the same footage.
Render files and generated media pile up
Apple's Final Cut guide says unused render files accumulate when you change a timeline, update Final Cut Pro, macOS or plug-ins, or move a library between Macs with different macOS versions.
How to delete render files in iMovie
This is the one control iMovie gives you to free space without removing any media.
Steps
- Open iMovie, and open the libraries you want to clear.
- Choose iMovie › Settings, or press Command-Comma.
- Next to Render Files, click Delete.
Apple says this removes render files from your open libraries, freeing storage space, and that no imported media is removed. Libraries that aren't open keep theirs, so open each library first.
Is it safe to delete render files in iMovie?
Yes. Render files are previews iMovie made from your clips, and it renders again when it needs to. The cost is time: playback of effects and exports may take longer until they're rebuilt. Apple warns that deleting them while a project is exporting can slow that export.
How much space will it free?
It depends on how much rendering your projects needed. Apple doesn't give a figure, so check the library in Finder with File › Get Info before and after. A library that's mostly imported clips gains little; one with long projects full of effects and titles can gain more.
Does iMovie have optimized or proxy media?
iMovie's guide doesn't describe optimized or proxy files, or a way to create them. Those are Final Cut Pro features, covered next.
Delete Generated Library Files in Final Cut Pro
Final Cut Pro's command removes render, optimized and proxy files for a whole library in one step. Apple's move guide recommends it before moving a library.
How to delete generated library files
- In the Libraries sidebar, select the library.
- Choose File › Delete Generated Library Files.
- Select Delete Render Files, then choose unused or all render files.
- Select Delete Optimized Media and Delete Proxy Media if you don't need them.
- Click OK.
Apple's guide says the selected files are deleted from your storage device. Nothing is lost, because Final Cut can make them all again from the original media.
Unused or all render files?
Unused removes render files nothing in the library uses any more, so current projects keep theirs. All frees the most space, and Final Cut renders again in the background as you work.
Apple notes that deleting all render files in an event also deletes the render files of projects in that event.
Should you delete optimized and proxy media?
Delete them when a project is finished, or before you move or archive a library. Apple says render files come back on their own, but optimized and proxy media have to be created again by hand, with File › Transcode Media.
If you edit on proxies, switch back to optimized or original media before sharing, as Apple advises. Exporting from proxies gives a lower-quality file.
Smaller commands for clips, projects and events
| Select | Choose | Removes generated files for |
|---|---|---|
| Clips in the browser | File › Delete Generated Clip Files | Those clips |
| Projects in the browser | File › Delete Generated Project Files | Those projects |
| Events in the sidebar | File › Delete Generated Event Files | Those events and their projects |
| A library in the sidebar | File › Delete Generated Library Files | The whole library |
Apple adds that the library and clip commands also affect generated files stored outside the library, not just inside it.
What Delete Generated Files doesn't remove
Original media, imported or external. Analysis files, thumbnails and waveforms, which live in the cache. Library backups. And Motion content or third-party effects, which Final Cut doesn't manage inside the library at all.
Can you stop render files from building up?
By default, Final Cut starts rendering in the background shortly after you stop working. Apple says you can turn background rendering off or change its timing in Final Cut Pro's playback settings. That saves space while you edit, at the cost of rendering by hand or at export.
Deleting events, projects and clips safely
Generated files are the easy part. To free more, you delete footage and edits, so first check what's the only copy.
Which items hold the only copy of your footage?
Anything you imported from a camera, a memory card or an iPhone and then erased from the device. Once the card is reused, the clip in the library is the original. The same goes for screen recordings and downloads you deleted after importing.
Media from the Photos library is different. Apple says photos and clips in Photos are available in iMovie without importing, so those originals stay in Photos.
How to delete an event in iMovie
- In the Libraries list, select the event.
- Choose File › Move to Trash.
If a clip is used in a project, iMovie asks you to remove it from the project first. To keep a few clips from an event, drag them to another event before deleting it, or Option-drag to copy them.
How to delete a project in iMovie
In Projects view, click the button to the right of the project's name and choose Delete Project. Then check the library for a new event named after the project, which holds its media, and delete that event if you don't need the clips.
Deleting in Final Cut Pro
Select clips or projects in an event and choose File › Move to Trash, or select an event and choose File › Move Event to Trash. Apple says the source media files go to the Trash, except media other projects in the library still use, which stays.
Until you empty the Trash, you can still change your mind. Apple warns that once it's emptied, the deleted clips and their media can't be restored. A library always keeps at least one event.
Export what you'll want to watch
A finished movie is far smaller than the footage behind it. Before deleting a project's events, export it with File › Share › File in iMovie, or with File › Share in Final Cut Pro. Keep the export, and the raw footage can go.
| Item | Safe to remove? | Where |
|---|---|---|
| iMovie render files | Yes, made again when needed | iMovie › Settings, Render Files |
| Final Cut render files | Yes, made again in the background | Delete Generated Library Files |
| Optimized and proxy media | Yes, but recreate them by hand | Delete Generated Library Files |
| Events and imported clips | Only if you have the originals | File › Move to Trash in the app |
| Projects | Only if you've exported or won't need them | Projects view or the browser |
| The library itself | Only after moving or archiving it | Finder, as Apple's move steps describe |
Moving a library to an external drive
If you need the footage but not on your Mac, move the whole library. Both apps support it, with a few rules about drives.
Moving an iMovie library
Apple's steps:
- Quit iMovie.
- In Finder, choose Go › Home, open Movies, and drag iMovie Library to the external drive.
- When it's copied, double-click the library on the drive to open it in iMovie. Click OK if asked to allow access to a removable volume.
- Make sure the moved library has all your media.
- Drag the original from the Movies folder to the Trash, then empty the Trash.
From then on, iMovie saves new imports and projects to the library on the drive.
What if the drive isn't connected?
Apple says iMovie opens the moved library automatically when the drive is connected. Without it, iMovie opens a new, empty library in your Movies folder and saves new work there. Connect the drive and double-click the library to go back, then move clips, events and projects between libraries as needed.
Moving a Final Cut Pro library
Apple's support article suggests deleting generated files first, to move less. Then select the library, choose File › Reveal in Finder, quit Final Cut Pro and drag the library to the drive. Check it opens with all its media, then drag the original to the Trash.
Inside the app, File › Copy to Library › New Library does the same with more options. Select Copy media stored in external locations to bring linked footage along, and leave optimized and proxy media unselected to save space.
Which drives work?
| App | Drive format | Not supported |
|---|---|---|
| iMovie | APFS or Mac OS Extended (Journaled) | SD cards, flash drives, network storage, Time Machine drives |
| Final Cut Pro | APFS | ExFAT, NTFS, Time Machine drives |
Apple's Final Cut article warns that drives often come formatted for Windows, and asks you to reformat them as APFS in Disk Utility first. Erasing a drive removes everything on it, so copy anything you need off it beforehand.
Consolidate before you move
Projects can use media from outside the library, from another drive or folder. iMovie's File › Consolidate Library Media copies it in. In Final Cut Pro, click Consolidate in Library Properties, or choose File › Consolidate Library Media.
Apple's rule for Final Cut: consolidating out of a library to an external folder moves the files; consolidating into a library copies them. If the media was already external and no other library uses it, Apple says you can delete the originals afterwards.
Keep the library small without moving it
In Final Cut Pro, Library Properties › Modify Settings can send new media and cache files to another drive while the library stays on your Mac. Apple notes existing files stay where they are, though Final Cut offers to move active render files when you change the cache location.
Final Cut Pro's automatic library backups
Final Cut Pro backs up each library at regular intervals, and people often find the backups when hunting for space.
What do the backups hold?
Apple says backups include only the database portion of a library, not the media. They're standard library files named with the date and time, such as a name starting with the year, month and day. That makes them small next to the library itself.
Where do the backups go?
By default, to a backups folder in your Movies folder, which Apple's guide calls Final Cut Pro Backups. Apple says Final Cut automatically deletes backups more than several days old, so the folder doesn't grow without limit.
How do you restore one?
Select the library, choose File › Open Library › From Backup, pick a time from the Restore from menu, and click Open. The backup opens as a separate library, so you can copy back the projects you need.
Should you turn backups off?
In Library Properties › Modify Settings, the Backups menu can point to another drive or choose Do Not Save. Apple recommends backing up to a different drive from your media. Moving backups there makes more sense than turning them off, since they cost little and can rescue a damaged library.
Do backups go with a copied library?
No. Apple notes that library backups aren't copied when you copy a library. If you move a library to another Mac, its backups stay on the old one.
iMovie Theater, old projects and other leftovers
A few more places can hold video from these apps. Most are small, but one can be large.
What happened to iMovie Theater?
Apple says sharing to iMovie Theater is no longer supported. If you shared movies there in older versions, you can still view, share and delete them with Window › Go to Theater.
To keep them, click the More Options button below a movie, choose Copy to File, then import the file into Photos. Apple suggests deleting them from the Theater once they're in Photos.
How do you delete movies from iMovie Theater?
Click More Options below the movie and choose Delete. Delete from iCloud keeps it on your Mac; Delete Everywhere removes it from iCloud, your Mac and your other devices. Apple says your source project and media aren't deleted either way.
Projects from older iMovie versions
If you updated from an earlier iMovie, the original projects and events may still be on your Mac or on drives you connected, beside the updated library. Apple says the update copies them, so check that the new library has everything before you remove the old copies.
What about the apps themselves?
iMovie is free in the Mac App Store, listed at 3.6 GB, and its listing asks for macOS 26.4 or later and 3.5 GB of available disk space. Final Cut Pro is listed at 6.4 GB and asks for 7.2 GB. The libraries, not the apps, are what grow.
Does deleting iMovie delete your movies?
No. Apple notes that deleting an app doesn't remove the documents you made with it, and libraries are documents in your Movies folder. Removing iMovie frees the app's space only; the library stays, and you'd need iMovie again to open it.
Motion content and third-party plug-ins
Effects and titles made in Motion are stored in the Motion Templates folder in your Movies folder, unless you consolidate them into a library. Apple says third-party FxPlug effects aren't managed by the library at all; they're installed with their makers' own installers.
Exported movies and screen recordings
Exports often end up in Movies or Downloads and are forgotten. So are screen recordings imported into a project. Screenshots and screen recordings pile up in their own ways, and duplicates of clips you also keep in Photos are worth checking with the post on finding duplicate photos.
Deciding what to keep
Most of a video library's size is footage, and footage is the hardest thing to get back. Decide by asking what's the original.
A quick way to decide
- Finished projects you've exported. Keep the export. Archive the library to a drive, or delete its events if the raw footage doesn't matter.
- Projects you're still editing. Keep everything, delete render files now and then, and use proxies in Final Cut.
- Footage you never edited. Move it to a drive, or delete the events if the clips are also in Photos or on a card you keep.
- Old libraries from earlier versions. Check the updated library, then remove the old copies.
Mistakes to avoid
- Deleting files inside a library package in Finder. The library still lists them, and it can be damaged.
- Deleting clips one by one in iMovie and expecting space back. Only deleting a whole event frees space.
- Erasing the camera card before checking the import. The library may then hold the only copy.
- Trashing the original library before opening the copy. Check the moved library has all its media first.
- Storing a library on a Time Machine drive or a flash drive. Apple doesn't support either.
- Zipping a library to save room. Video is already compressed, so compressing files gains little here.
Other apps that keep media the same way
Photo editors keep generated files too: Lightroom Classic's previews play much the same role as render files. Apple's music apps download sounds rather than footage, covered in the GarageBand and Logic Pro sound libraries.
Movies bought in the TV app aren't in either library. TV app and Podcasts downloads live elsewhere and have their own controls.
If footage lives in Photos rather than iMovie, the post on moving the Photos library to an external drive covers that library's own steps.
How the app does it
Wombit shows every iMovie and Final Cut Pro library in your home folder on the map with its real size, including ones you'd forgotten, and explains each from the catalog: what's inside, what can be made again, and how to free space in the app itself.
~/
**/ *.imovielibrary An iMovie library: the video and photos you imported, your projects, and render files iMovie creates.
Review first · Explained only: the app shows you how
~/
**/ *.fcpbundle A Final Cut Pro library: your events and projects, media copied into it, and render, optimized and proxy files.
Review first · Explained only: the app shows you how
Both are Review first, because they hold footage and edits that may exist nowhere else. The library packages are protected: the app never moves one or anything inside it. It points you to Render Files in iMovie's settings and Delete Generated Library Files in Final Cut Pro instead, and nothing about them starts checked.
File names and paths never leave your Mac. The scan, the map and the explanations are free. Cleanup, for items the app can move to the Trash, is PRO, one $4.99 payment with lifetime access. Every Pro tool's review is free to open, so you see what would go and why before you buy.
Frequently asked questions
Is it safe to delete render files in iMovie?
Yes. Render files are previews iMovie makes from your clips, and Apple says deleting them removes no imported media. iMovie renders again when it needs to, so playback and exports may take longer for a while. Choose iMovie › Settings and click Delete next to Render Files.
Why is my iMovie library so big?
Because it holds every clip you imported, and video is large. Deleted projects can leave their media behind as a new event, and deleting single clips doesn't free space. Render files add more, and they're the one part you can remove without losing anything.
Why doesn't deleting clips in iMovie free up space?
Apple's iMovie guide says you have to delete an entire event to free storage space. Deleting clips from an event doesn't, and pressing Delete on a clip only marks it as rejected. Move the clips you want to keep to another event, then delete the old one.
Can I delete the iMovie library?
Only if you've exported or copied everything you want from it. The library holds your imported footage and projects, which may exist nowhere else. To free space without losing anything, move it to an external drive with Apple's steps instead.
What does Delete Generated Library Files do in Final Cut Pro?
It deletes the library's render files, optimized media and proxy media, whichever you select. Original media isn't touched, so Final Cut can make them all again. Render files come back on their own; optimized and proxy media have to be transcoded again by hand.
Where are Final Cut Pro library backups stored?
By default, in a backups folder in your Movies folder, set per library in Library Properties. Backups hold only the library's database, not media, and Apple says Final Cut deletes those more than several days old by itself.
Can I delete files inside a Final Cut Pro library in Finder?
No. A library is a package that Final Cut Pro manages, and changing files inside it in Finder can damage it. Use Delete Generated Library Files for generated media, and delete events and clips in the app, which moves their source media to the Trash.
How do I move my iMovie library to an external drive?
Quit iMovie, drag iMovie Library from your Movies folder to a drive formatted as APFS or Mac OS Extended, and open the copy in iMovie. Once you've checked it has all your media, move the original to the Trash. Apple doesn't recommend SD cards, flash drives, network storage or Time Machine drives.