Resize Partitions in Mac OS X with Disk Utility

Nov 20, 2009 - 11 Comments

You can easily resize any disk partition in Mac OS X using the included Disk Utility app, located in /Applications/Utilities, you can even resize a mounted volume but that’s not the best idea in the world. Before you go messing around and resizing your partitions, be sure to backup your data in case something goes wrong.

Since Mac OS X Leopard (and obviously Snow Leopard) you can grow or shrink HFS+ (Mac OS X) Partitions on the fly, with the resizing done live regardless of whether the drive is internal or an external drive.

[ tip idea and animated gif from CreativeTechs ]

DiskUtility-Resize

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Posted by: Paul Horowitz in 10.5, 10.6, Mac OS X, Tips & Tricks, Utilities

11 Comments

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  1. Jasper van den Bergen says:

    I see that the article is almost a year old, but I have a question about this and hope you can still answer this.

    My Mac HD is also formatted as Mac OS Extended (journaled), but won’t allow me to resize (enlarge) this partition. I haven’t got a ‘drag’ corner.

    It says something about being my startup disc, which isn’t being mentioned in the article.

    Is this what causes the problem?

  2. John says:

    Did you ever get an answer? I’ve got the same problem and haven’t found a solution yet. Thanks.

  3. Joachim says:

    Disk Utility does not let you resize a partition that has a Master Boot Record (MBR). You can see at the bottom of the window in the information if that is the case for your partition. These type of partition are the ones that are used for booting a system.

  4. Ranvir says:

    Yes thats right. Any application cannot be applied to resize the boot volume of the current system. It must be attached as an external hard drive to resize the boot volume. Well , a few days ago I have tried the Stellar Partition manager successfully.

  5. Kesari says:

    Was looking for some partitioning information and stumbled across this posting. I tried out of curiosity and it works perfectly fine. If we have multiple partition on a disk (internal/external), we need to choose the main disk from the Disk Utility by clicking on the disk and not on the partition and select tab and it works beautifully. I did this on my boot volume (system partition) while running applications without any issue I could partition. But I see that this is not helpful for my situation as this doesn’t let one to grow the partition. i.e. say if one has 100 gb x 3 partitions, we can’t resize and increase the size like, say make one partion 50 gb and use the 50 gb to make the other partition 150gb. But you can free up 50gb and create a new partition to make it 2x50gb and 2x100gb.

  6. John says:

    Use first aid and it should remove the master boot record. It worked for me.

  7. peleks says:

    try to boot with recovery hd and then resize partitions

  8. peleks says:

    found out issue, if u want to transfer files instalations to another disk – if ur old disk is for example 500gb and u want to transfer to 256gb ssd it will say – not enought disk space even if ur 500gb disk is filled with 100gb info, u need to resize it first to a size your new disk have

  9. AppleMVP says:

    Hi, I got a question as simply as it gets about Disk utility. Some time ago I did two partitions on my Hard Disk, One called Macintosh HD with 435,00 GB long and other One called Windows 7 with 203,00 GB long, it was planned to install Windows 7 on the second partition but i´d definitely not since I purchased a laptop with Windows 7 on it.
    So now I want to delete the Windows 7 partition and enlarge the main partition so that I just have one partition of 638,00 GB long. the question is ¿the process of enlarge the main partition from 435,00 GB till 638,00 GB would end up on a lost of main partition data? Thank you very much in advance.

    • Paul says:

      You can delete the Windows 7 partition without impacting the primary OS X partition with Disk Utility. Just remember to back up your Mac beforehand just in case something goes wrong, which there is always a chance of when editing file systems and partitions.

      • AppleMVP says:

        I know that, I do remark my question ¿the process of enlarge the main partition from 435,00 GB till 638,00 GB would end up on a lost of main partition data?

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