Tech Tip: increasing the size of a Bootcamp partition with free tools

I ran out of space on my Bootcamp partition, so wanted to increase its size. Several applications promise this functionality, but they cost money, and I like to see if I can do things for free first. In this case, you can.

I run Windows on my Mac using Bootcamp and VMWare Fusion (Bootcamp lets you install Windows on to a partition on the hard drive so you can boot into it, VMWare lets you run Windows as a Virtual Machine inside OS X. VMWare can optionally run your Bootcamp partition as a VM, giving you the option to boot into Windows or run it as a VM alongside OSX, which is what I do most of the time). If you don’t use VMWare, ignore the steps that mention it.

I have a 2010 iMac running OSX 10.6.7, with Windows 7 64 bit installed on a Bootcamp partition, with VMWare Fusion 3 allowing me to run this as a virtual machine. I increased Bootcamp partition from 40GB to 100GB using the following free tools:

  1. Disk Utility (OSX utility)
  2. GPartEd: download from and burn to CD to create a bootable disk
  3. rEFit: download from and burn to CD to create a bootable disk

You will also need a Windows installation disk for the version of Windows you have installed.

Remember BACKUP YOUR DATA FIRST for both OSX and Windows. Something could go wrong.

The steps below worked perfectly for me. I used the following as a guide at The only thing I changed was that I used the standard version of GPartEd since it now supports NTFS partitions.

  1. Use Disk Utility in OSX to shrink your OSX partition. This leaves unallocated space between the OSX partition and the Bootcamp partition.
  2. Restart and boot from the GPartEd CD. Use all the default settings. Use the Resize/Move function to increase the size of the Bootcamp partition to fill up the unallocated space available on the drive.
  3. When GPartEd is finished, restart and boot from the rEFit CD. Select the Partitioning Tool. This will rebuild the MBR table to match the GUID table.
  4. Now restart again and boot from the Windows CD. Select the Repair option and the tool will rebuild your Windows installation to recognise the resized partition.
  5. Restart and boot into Windows and let it run chkdsk.
  6. Restart and boot into OSX.
  7. The final step is to get VMWare Fusion to once again recognise the Bootcamp partition as a virtual machine. Open the terminal (in Applications/Utilities) and enter the following (including the quotes):
    rm -dfr “/Users/$/Library/Application Support/VMware Fusion/Virtual Machines/Boot Camp”
    (where $ is your username)
    This removes the previous data about the Bootcamp partition. Launch VMWare Fusion, go to Home, and choose Run Windows from your Boot Camp Partition.
  8.  It should all be working now 🙂

2 thoughts on “Tech Tip: increasing the size of a Bootcamp partition with free tools

  1. Justin

    Just want to thank you. This worked like a charm! I would only add a couple of things to the instructions above.

    1. To boot from a CD on the Mac, press the “C” key after you hear the startup tone (or before the apple logo shows). I was holding the option key, but when I selected the “Windows” CD option, it didn’t boot correctly. However, it worked fine when I booted by pressing the “C” key.

  2. Emmanuel

    Like Justin said, this worked like a charm!!! I did not use Disk Utility to shrink my OSX partition. Looks like GParted took care of that.

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