How to increase C: drive space with ease?

The most common issue in Windows platform is disk space usage especially for system C: drive. After running the personal computer or server for a period of time, free space in C drive becomes insufficient. It cannot be better if you can increase C: drive directly, right? Nobody would like to start from scratch, however few people has professional skill to complete this task. In fact, it is very easy, here I’ll show you how to increase C: drive partition size in Windows Server 2016/2012/2008/2003 (R2) and Windows 10/8/7/Vista/XP.

Low disk space in C drive

As I said above, it is common issue in Windows all editions. After running the computer for a period of time (some people feedback 3 months), the system C drive is running out of free space and becomes full. In this situation, in Windows XP/Vista and Server 2003/2008, you’ll receive the Low Disk Space warning. In Windows 7 and later editions, C drive (including all data drives) will be marked as red when opening My Computer or Explorer.

If you have seen the low disk space alert and red C drive, try to increase C drive as fast as possible, otherwise, you have no space to install Windows update, system reboot unexpectedly or even crash.

Why C drive can be re-sized

Some people doubt if the disk drives really can be resized, especially for the system partition, because Operating System running from there. Actually, it is easy to understand: every drive has used and unused area, all files are stored in used area and controlled by File System of this drive. You can modify the parameters in File System related to used and unused area. For example, you can reduce a drive and then part of the unused space no longer belong to this drive. Similarly, you can increase a drive, but the precondition is there is unused area.

How to increase C drive space

Luckily, there are tools to help you resize partitions without doing it by yourself. Microsoft provide built-in utility to reduce and increase the size of partitions, but due to the limitations, neither of the utilities is the right tool. The best choice is 3rd party professional partition resizing software, which is much easier and powerful.

Increase C drive free space with Windows built-in utility

Dispart command from CMD

For Windows Server 2003 and XP, to increase C drive space, you have to run from CMD.

Step1: Press ‘Windows‘ and ‘R‘ key on the keyboard, type ‘cmd‘ and click ‘OK‘ or press ‘Enter’.


MS-DOS command line window will be opened.

Command windowStep 2: In the command line window, type diskpart and press ‘Enter’.

Run Diskpart

Step 3: Type “list volume” to display the existing volumes on the computer.

List volume

Step 4: Type “select volume X”, X is the number or drive letter of the partition that you want to expand.

Select volume

Step 5: Type extend.

Diskpart extended

Key limitations increasing C drive with diskpart:

  1. C drive must be formatted as NTFS.
  2. There must be contiguous Unallocated space behind C drive.
  3. Different with extending data drive, C drive can only be extended by running Diskpart from bootable CD.
  4. No preview option, incorrect operations cannot be undone.

Disk Management snap-in

From Windows Vista, Microsoft added GUI function in Disk Management to shrink and extend partitions. Yes, it is easier to use, but the limitations keep the same with Diskpart command except point 3 (you can do in Windows without bootable CD).

Increase C drive disk space with partition software

The task to increase C: drive space becomes much easier if you use 3rd party partition software.

Step 1: Download NIUBI Partition Editor, right click D: drive and select “Resize/Move Volume“.

Drag to resize

Step 2: In the pop-up window, drag the left border rightwards to generate free Unallocated space.

Shrink d drive

Drag to resize

Click OK and back to the main window, where 20GB Unallocated space created behind C: drive.

Unallocated space

Step 3: Right click C drive and select “Resize/Move Volume” again, in the pop-up window, drag the right border rightwards to hold the Unallocated space.

Extend C drive

Hold unallocated space

Click OK and back to the main window, where C drive extended to 60GB by holding the 20GB free space from D. Press Apply on top left to execute, done!

Partition resized

Video guide to increase C drive free space

(Recommend full screen by clicking the square at bottom right of this video)


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