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How do I create a new partition on my hard drive?


  1. My C drive has 465GB and E reserve drive maybe 100GB
  2. I do not have any unallocated space anywhere
  3. Therefore I cannot partition the hard drive
  4. I want a partition with 100GB to put Windows 10 on it

If you have enough free space on your C: drive, then creating a new partition is actually pretty simple.

I’ll show you the steps using Windows 7’s Disk Manager.

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Free Space

I need to reiterate the need for free space on your C: drive. While the C: partition may take up 465GB on your machine, if you want to create a 100GB partition, you’ll need to have at least that much – ideally more – unused space within your C: drive.

And yes, that means you’ll need to make room by deleting files if you don’t.

Filling up a 465GB drive these days takes a bit of work, so I can’t really guess as to what on your machine might be using up all that space – if indeed the drive is full of data. What I can recommend is that you check out my article Where’s my disk space going? for a tool and process to help identify what’s using the most space.

Then decide what can be deleted, or perhaps moved off-line, to free up space on your C: drive.

If your C: drive has over 100GB of free space, then you’re in good shape.

Defrag and defrag again

Before you begin, I recommend defragging the disk. In fact, I recommend you run defrag a couple of times.

The issue here is that making files contiguous – the defragmenter’s primary function – isn’t enough. We actually need to move as many files as possible to the “front” of the disk. Defrag will do this as well, just not very efficiently.

Depending on how fragmented the files are on your machine, you may need to run the defragger multiple times. We’ll see in a moment exactly how we’ll know when we’ve done it enough.

Shrink the C: volume

We start by shrinking the C: drive which will take it from its current size to something smaller. In your case, you might take your 465GB C: and shrink it down to 350GB, freeing up over 100GB that we can then use for something else – like a separate partition.

Start by pressing the Windows Key plus R, and running diskmgmt.msc.


In Disk Manager, right click on the C: drive and click on Shrink Volume.

Shrink Volume

Disk Manager then examines the volume.

Querying for Space

Disk Manager is looking to see, given the way that files are currently laid out on the drive, how much smaller the drive can be made.

Shrink Size

My 100 gigabyte example drive (102,292 megabytes, to be precise) could be shrunk by as much as approximately 68 gigabytes, which would leave the existing drive at a smaller 33 gigabytes in size.

This is where you might need to go back and defragment again.


  • The “Size of available shrink space in MB” is less than you need, say 100 gigabytes, or around 102,400 megabytes


  • There is still enough free space on the C: drive to make up the difference

Then defragmenting again is the only course of action. In fact, you may need to repeat the defragmenting until the available shrink space is as large as you need or larger.1

Enter the amount you want to shrink the drive – I’ve selected 50,000 megabytes, or about 50 gigabytes, in my example. Click on Shrink.

Shrink Amount

After a few minutes, you’ll be returned to Disk Manager, displaying two partitions where the old C: used to be: a new, smaller C:, and unallocated space.

Empty Space

Create the new volume

In order to actually use the unallocated space as a partition, we need to create a partition and format it.

Right click on the unallocated space, and click on New Simple Volume.

New Simple Volume...

Click on Next to enter the resulting wizard, and you’ll be given the option to specify a size for the new partition.

The default is to use all available space, which is exactly what we want. Click Next.

New Partition Size

You’ll be offered the ability to assign the new partition a drive letter. The default is typically good enough, so click Next again to be taken to formatting options.

Once again, the defaults are probably just fine, though you might want to give the drive a different label to more easily identify it in Windows Explorer later.

Formatting Options

Click Next to view a summary page, and then click Finish, and the new drive is formatted and made ready for use.

You can then open Windows Explorer to confirm that the new partition has been created.

New Drive in Explorer

About Windows 10

You’d indicated that this was so you could install Windows 10 in a separate partition.

I gotta say, I’m not a fan.

I’m OK with testing Windows 10; it’s the dual-boot scenario I’m reluctant to recommend. I’ve seen it confuse and cause problems for some people. If it works for you, that’s fantastic, but I prefer either of two other approaches:

  • Backup, upgrade, and test in place. If it’s not to your liking, restore the backup image.
  • Install Windows 10 in a virtual machine.

I’ve done the latter.

Be aware that an install into a separate partition is considered a “clean” install, and will not qualify you for the free upgrade. Only the upgrade path I’ve listed above can do that.


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Footnotes & references

1: Naturally, there are limits. Unfortunately, there may be unmovable files preventing a complete defragmentation. The only solution I’m currently aware of is to perform a complete image backup of the C: drive, followed by an image restore. With the correct tools, such as Macrium Reflect, the net result should be a fully defragged hard drive.

18 comments on “How do I create a new partition on my hard drive?”

  1. Some times, due to files that are in use or that can’t be moved for any reason, you can’t perform a complete defragmentation. Normaly, in this case, you can schedule a boot time defragmentation. That way, there are no files in use, apart for the defragmenter itself.
    Even in this case, it’s still possible that a specific folder/set of folders, like the “System volume information”, to be defragmentation resistent.
    If you use some third party defragmenter, you may have the option of pushing large and seldom accessed files toward the end of the disk. If you want to shrink a volume, that option must obviously be disabled.
    If you just want to compact the files toward the beggining of a drive, then a simple free space consolidation could be enough. In that process, no efforts are actualy made to defragment the files, just push everything toward the beggining of the disk and leave all the free space at the end.

  2. Hi Leo,

    You mentioned installing Win 10 in a virtual machine. My only experience with ‘virtual’ anything is mounting my backups on virtual drives on my main computer. So when you talk about mounting Win10 on a virtual machine, do you have to put it on a different computer, or do you mean there is a way to mount it virtually on your main computer in a different virtual drive? I have lots of space free (over 650 GB) on my hard drive, if that’s a concern.

    I would like to get used to Win 10 slowly. I have two computers, Vista and Win 7 and am happy with those. I just got Win 7 this year and it took forever to get used to from Vista making the change over all at once, and I don’t want to go through that again with Win 10 which I think would be even worse. But if I could play with Win 10 ‘on the side’ so to speak, it would be perfect. But assuming this is possible, as I described, can you switch from ‘virtual’ to real, and without paying for an upgrade.

    Some say ‘there are no dumb questions.’ Hope that applies here. :)

  3. The reason why Windows won’t let you shrink the volume is as the screenshot suggested, because there are immovable system files at the very end of the volume, as this screenshot from utility shows us. there are multiple things you could try to work this around.
    1. Run the Disk Cleanup Wizard, making sure to remove the hibernation file and all restore points.
    2. Disable System Restore
    3. Disable the pagefile ( Open up System in Control Panel, then Advanced System Settings \ Advanced \ Performance \ Advanced \ Change \ No Paging File.
    4. Disable kernel memory dump. In the same Advanced Settings, go to Startup and Recovery \ Settings and then change the Write debugging information drop-down to “None” to disable the kernel memory dump.
    5. Disable Hibernation mode in your power options \ advanced power options screen.
    Reboot the machine, and then delete your c:\pagefile.sys file, following these instructions if you are having issues.
    details about the fix and cause of this problem, see

  4. If Windows has trouble performing, perhaps because of “unmovable files” then try EaseUS Partition Master, which Leo has also recommended. I used it just last week on my Windows 10 installation and it worked like a charm when Windows said “No way!”

  5. Leo,
    I have a Seagate 3T drive, I am running 8.1, but I can not get past the 2T limits. I have looked at the seagate web site for help , possibly drivers, but I can not figure this out.
    I have to be careful due to the fact of having the OS in drive C which is an SSD drive and the related files are on the E drive which is the 3T drive. Using the built in Windows partitioning program is not an option and will not allow me to do it, probably it is needing drivers to get past that barrier.
    I tried upgrading to Windows 10 but ran into so many of my files having issues that I had to go back to 8.1.
    I own Partition Magic but no help here either. I have 745 Gigs I would like to recover for use but I do not have the knowledge with these new drives to make this happen.
    I appreciate your help.

  6. Excellent – however it needs to be mentioned that if you have an SSD drive just be careful – do not defrag it and do not remove the over provisioning


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