An iMovie library holds all the media and data used to make movies in iMovie. If your iMovie library is large and you want to free up storage space on your Mac, you can move your iMovie library to an external storage device.
Before you move an iMovie library, it's a good idea to back up your Mac.
Moving your library to an external storage device doesn’t affect any iMovie Theater content you have moved to iCloud.
Prepare your external storage device
You can store your library on an external storage device such as a USB drive or Thunderbolt drive formatted as APFS or Mac OS Extended (Journaled). Apple doesn’t recommend storing iMovie libraries on storage devices like SD cards, USB flash drives, or drives shared on a network.
You can’t store your library on a storage device used for Time Machine backups.
Move a library to an external storage device
- Quit iMovie.
- Select your external storage device in the Finder, then choose File > Get Info.
- If the information in Sharing & Permissions isn’t visible, click the triangle , then make sure the “Ignore ownership on this volume” checkbox is selected. If it's not selected, click the lock , enter an administrator name and password, then select the checkbox.
- Click your desktop to make sure that you’re in the Finder, then choose Go > Home from the menu bar at the top of your screen.
- Open the Movies folder, then drag the file named iMovie Library to your external storage device.
- When the library file is finished copying, double-click the library file on the external storage device to open it in iMovie. If an alert appears asking you to give iMovie access to a removable volume, click OK.
If you clicked Don't Allow, in the Finder choose Apple menu > System Preferences, click Security and Privacy, then click Privacy. Click Files and Folders in the sidebar, then select "Removable Volumes" under iMovie.
- Make sure the library you moved contains all your media, then drag the original file from the Movies folder on your Mac to the Trash.
If you disconnect the external storage device
When your external storage device is connected to your Mac, the library you moved there opens automatically when you open iMovie. If you disconnect the external storage device containing the library, iMovie opens to a new, empty library created in the Movies folder on your Mac, and iMovie then uses that new location to save any projects you create and media you import.
If you want to open the library you moved to an external storage device, you can open it again after you reconnect that storage device. You can then move clips, events, and projects between libraries.