Is there a method/utility to actively resize the partitions on a dual-boot MacBook Air, without destroying the contents?

I made the Windows Partition too small initially, and all the places I've looked have stated that resizing now using Boot Camp will destroy all data on the Windows 7 Partition.

How can I grow the Windows 7 partition into the available space (I can use Boot Camp to shrink the OS X partition without any problems)?

  • And the result: When I scheduled the boot-time chkdisk for winclone, something went really, really bad. From that point on, the Win7 partition failed to boot, continuously looping on a BSOD at boot-time. I had hoped that I could still take an image, but the image was (as expected) still exhibiting the problem. End result: Manual reinstall of Win7 OS :( Lots of good advice and ideas, but I would recommend anyone attempting to do this be very careful and have a backup handy - as this process is very prone to failure. – jbehren Feb 9 '11 at 13:11
  • Seems there are a few possibilities. iPartition worked great for me. – mb21 Sep 2 '14 at 15:48

GParted should make it possible (I haven't used it), see comments.

The best way (that I have successfully used) is to use a utility to

  1. Clone the Windows partition to an external drive (or just to the OS X partition if you have room (also keep in mind this is risky – it's good to have the full backup off the disk in question), using Winclone within OS X. It just creates an image file that you can move around to wherever you have space, until you do the restore.
  2. Erase the Windows partition (it's ok, because you have the clone)
  3. Create your new partition however large you want, using the Boot Camp utility within OS X
  4. Restore the Windows cloned image to the new, larger partition
  5. Use the utility to "expand to all free space"

Also, I would run a "disk check" on the Windows partition twice before creating the clone with winclone. Otherwise, restoring will most likely fail.

You can follow some of the steps from this question.

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  • I have done exactly this. After you restore the Windows partition, it will check itself for errors, which may well take a few hours. So all in all, it takes a while, but resizing a Windows partition can be done. – bastibe Feb 8 '11 at 16:59
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    This is wrong. You can easily grow and shrink Windows (FAT and NTFS) partitions with gparted. – Cajunluke Feb 8 '11 at 17:59
  • @CajunLuke this solution does work, as I've done it multiple times. As far as growing and shrinking the windows partition with gparted, if you can confirm that it works on Mac hardware with a bootcamp set up, then it is an alternate solution, but it does not take away the validity of doing it this way. If you can confirm it works on Mac hardware with bootcamp setup, I'll strike the first sentence, but the rest is still valid. – xdumaine Feb 8 '11 at 18:02
  • Yes, the first sentence is what I was objecting to. Your solution will work, and (to be honest) is probably safer, if way less convenient. And, yes, it works on a Mac when booted into a Linux livecd, both PowerPC and Intel. – Cajunluke Feb 8 '11 at 18:05
  • @CajunLuke fixed; see edits. – xdumaine Feb 8 '11 at 18:10

In this method, you don't need to save any image of your Windows partition at all. Just doing these 2 easy steps, you will be able to extend your Windows (system) partition.

  1. Start your machine in Mac OS

    1.1. Go -> Utilities -> Disk Utility

    1.2. Click on your hard drive ID -> Partition (tab)

    1.3. Shrink the Mac partition as much as you need

    1.4. Click on "Apply" button

    Now you have an unallocated space in your hard drive

  2. Restart to Windows

    2.1. Download the MiniTool Partition Wizard from this link. The Home version of this software is free for all users and you can download it from Download.com as well.

    2.2. After installing and running Partition Wizard, click on the system partition of your Windows -> Move/Resize

    2.3. Extend the system partition as much as you need, click on OK -> click on Apply You may be asked to restart your Windows.

Enjoy free fresh space on Windows!

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  • I did just that before I saw this answer. What happened is, after shrinking the Mac partition, you can't boot into Windows anymore – im_chc May 1 '19 at 17:13

GParted can resize NTFS partitions. It has a Live CD, but I have no idea if it works on Macs.

FWIW, extending a partition is simple. Shrinking is tricky.

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Last I heard, Disk Utility can do this. No one way is safer than any other, but I've never heard of anything going wrong. It's like batteries, they say they can explode because they can, but they never do.

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    This is not correct. Disk utility cannot resize the windows partition. It can only create separate partitions on the HFS+ Journalled (or other OS X compliant file systems) and resize them if they are OS X compliant. – xdumaine Feb 8 '11 at 14:45
  • They must have added this feature, because I've just been using it successfully using 10.7.4.. – André Hoffmann Jul 6 '12 at 1:05
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    No it is not possible, even in 10.8. You have never been able to resize an NTFS partition with Disk Utility. – Nathan Moinvaziri Aug 28 '12 at 9:50

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