I love iMovie and used it to create several projects on my wife's iMac. I'd like to move all my iMovie resources (from an HD camcorder and my iPhone) to my Macbook Air but I don't feel there is enough hard drive space for me to do so.

Has anyone here used iMovie sourcing documents from an external hard drive? Could you comment on the performance? I am not sure if I should be looking at an external thunderbolt hard drive, a usb3 drive, or if even a usb2 drive would suffice as I am not a heavy user.

  • What kind of video resolution are you dealing with here? In general I am a fan of getting the fastest drive/connection possible. If price matters than think about splitting the priorities. Find the cheapest hard drive with the fastest connection (that has the longest warranty)
    – Andrew U.
    Feb 25, 2014 at 14:42
  • 1
    Although USB 3 might be faster, I worked with USB 2 drives for years without issues. As I am aware, iMovie works with 'reference' files in which all your edits are stored, these are small files. Only exporting the movie will take some time limited by your CPU and USB throughput. Feb 25, 2014 at 17:37

3 Answers 3


I haven't used iMovie specifically but I have used Final Cut Pro X. And AFAIK they source media the same way.

Generally, it works excellently if you keep the following things in mind:

  1. The external drive needs to be "fast enough" (Basically: USB 3 or Thunderbolt)*
  2. To save power most external HDDs will enter sleep mode after a certain amount of inactivity. When that happens, it'll generally take a couple of seconds for OS X to wake the drives when you start poking around in iMove again.

(Optionally, HDD sleep can be disabled in System Preferences > Energy Saver but unchecking Put hard disks to sleep when possible)

Short answer

USB 3 should be totally fine for you.

Long answer

"In the old days" (or on older Macs), when using USB 2 drives, you'd run the risk of not being able to read/write fast enough. But with your use-case and a modern Mac, that shouldn't be a problem.

The main rule: In general, the faster the drive, the better. This means Thunderbolt over USB 3 and USB 3 over USB 2 and so on. Opting for 7200 RPM instead of 5200 RPM is also a great choice. In the end it comes down to how much you're willing to spend.

I can't point to an official source but Apple-Certified trainer Larry Jordan has a great article that explains the above points in detail. Also, I work at media company so I have a bit of experience on this.

*I could throw numbers at you but since you mention "camcorder" and "iPhone" as sources, I'm guessing that telling you the number of ProRes 422 streams each connection type can handle, would be immense overkill :)


While I don't have specific stats to share, I was in he same situation this past December - a ton of video to edit in iMovie '11; however, not enough space on the hard drive of my MacBook.

I used a USB 3.0 external hard drive for both the events/clips and the iMovie project itself. I experienced no issues whatsoever. In fact, iMovie seemed to run better than when I was trying to edit with the videos bogging down my internal hard drive.

I created a two movies (2 and 3 hours long) on the external hard drive…so from my experience, you should be safe doing the same!


I have used USB2 7200RPM external drive as storage for videos - capturing them from camera, transcoding to allow slow motion. At that time I used Core Duo Macbook Pro and performance wasn't surprising. But if you have a lot of time then you can leave the Macbook to crunch the videos on external drive.

  • Just over the weekend I spoke with a friend who is also playing with video in Final Cut on his Macbook Air and it turns out that USB2 is terribly slow. He is thinking about upgrading at least to USB3 enclosure with SSD disk inside for active projects and to Thunderbolt disks for project storage.
    – ZXpower
    Mar 3, 2014 at 23:45

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