PC to Mac External Hard Drive Formatting

Written by MPS Consultant Sarah Goetz – for more help with this topic, visit Sarah at the MPS during her scheduled hours, visible on our Live Schedule.

If you doing major media editing, chances are you have an external hard drive from a variety of popular sources such as Western Digital, La Cie, and Other World Computing. Straight out of the box, most of these hard drives are formatted for use on both PCs and Macs in a format called FAT32. This also is the format for almost all flash-drives. For everyone who goes between the two operating systems, FAT32 is useful.

However, many multi-media users will run into quite a few problems with FAT32, especially if you are doing video editing and a working with large, un-broken files. FAT32 is particularly problematic for users working with video editing. FAT32 will only allow a Mac to write files that are less than 4-5GBs (roughly 10 minutes of standard definition footage). Practically, this means that if you are using your drive for Capture Scratch in Final Cut Pro, you will get the error: “Capture has been ended due to lack of disk space.” Or, outside of a video editor, if you try to put a file more than 4-5 GB on your drive you will get the error: “the operation can’t be completed because an unexpected error occurred (error code 0).

If you are running into these problems you might want to reformat your hard drive. WARNING: reformatting WILL DELETE everything on your hard drive. In the following instructions, you will be given advice about how to go about saving your data and reformatting. Before you proceed, take a look at the following pros/cons to make your decision on your drive formatting.

If you decide that reformatting your drive is the way you want to go, here’s a step by step guide on reformatting a hard drive with a Mac.

How to Reformat:

Check: Is your drive there? In a Finder window, look under devices, as well on your desktop to make sure your drive is connected.

Check: Get Info

Right-click or Command-click to Get Info about your drive’s formatting.

Check: Formatting and Permissions

Look at the information to see if your drive is already formatted correctly as Mac OS Extended Journaled. The image below shows a correctly formatted disk. Note that svg3 (Me) has both Read & Write permissions. This is necessary for you to be able to work with your disk. “Read Only” means you can only look at the information on the disk, not save anything to it. You do NOT want this.

Copy all your data to your AFS space:

VERY IMPORTANT! If you want to keep information that is currently on your drive, you will need to copy your data to a safe place like your AFS space or another drive. When you are finished formatting your drive, you can copy it back. Be patient, this will take time.

Go to Disk Utility:

1) Find your drive

2) Click “Erase”

3) Click on the “Format” drop-down Menu

4) Select the correct format, Mac OS Extended (Journaled)

5) Select “Erase”


Let the computer process everything and when it is finished, you can add your files back on to your drive and go on your merry way! Don’t forget to ALWAYS BACK UP YOUR FILES!

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  1. 2tbexternalharddrive
    Posted July 14, 2011 at 10:16 am | Permalink

    This post really help me. Now I can easily tell my customer to visit this post. Usually hard drive is initially installed with NTFS format. NTFS format is only for windows OS. If you want it work with both PC and MAC try FAT 32 as stated in the post.

  2. Matt
    Posted September 24, 2011 at 12:18 am | Permalink

    I found the tutorial very helpful as I own both Mac and PC. I find myself using Mac more but sometimes find frustrating to back it up via time machine, that would make a great tutorial!

  3. Dax
    Posted September 30, 2011 at 5:28 pm | Permalink

    Thanks. As a tech support professional, I feel like this info will come in handy one day.

  4. Hayley
    Posted September 12, 2012 at 5:39 am | Permalink

    This was extremely helpful!
    Thank you so much.

  5. Cisco
    Posted September 21, 2012 at 2:13 pm | Permalink

    Thank you!

  6. will.i.am
    Posted December 22, 2012 at 7:33 pm | Permalink


  7. Data Recovery
    Posted April 2, 2013 at 3:29 pm | Permalink

    Good guide, saves money on buying applications for a low level format. Disk utility does a good job!

  8. kenny
    Posted June 12, 2013 at 8:51 am | Permalink

    very helpfull thank you very much

  9. Bill
    Posted September 24, 2013 at 12:42 pm | Permalink

    Well, what if the mac doesn’t see the external harddrive in the first place?

  10. Posted January 18, 2014 at 2:35 pm | Permalink

    I have a 2012 27″, 2.7 GHz, Mavericks & 16GB memory. I am attempting to mount & use a Seagate 1.5 TB external HD as my time machine. Problems are: while it seems to accept the drive, after a few minutes I get a message ” cannot unmount the drive, backup failed”.
    Although the drive is reformatted to Mac OS Extended (Journaled) I cannot completely erase the drive and every time I shut down the computer it automatically dismounts and the ply way to remount it is to pull out the power plug on the HD and reconnect after a few seconds.
    I would greatly appreciate any available info

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