How to increase the volume of the ‘C’ disk:\\’ at the expense of the disk ‘D:\\’ without data loss

A question from the user


I recently ran out of space on the Windows disk - and the error ‘Not enough space on the system disk partition, this may be the reason…’ began to pop up in the tray next to the clock.

The fact is that on the ‘C’ drive:’ there really isn’t enough space - only 30 GB, but on another disk ‘D:’ - 420 GB (approximately 200 GB free). Is it possible to increase the volume of disk ‘C’ at the expense of disk ‘D’ without data loss?


Acer Aspire 5550 laptop, Windows 8 system, 500 GB hard drive (Seagate, if I’m not confused).


Most often, it is necessary to change the disk volume when installing Windows OS, the required size of the system disk was correctly calculated (also when buying a PC, it is often not very convenient to split the disk: either there is only one partition with Windows, or the size of the system partition is very small).

In general, such an operation to change the size of partitions can be done even without installing additional programs if you have Windows 7-11 OS installed (if XP, use the link to special software for formatting, splitting hard drives, link below).

Now I will show you by a concrete example where and how to click

Programs for working with hard drives (HDD) and solid-state drives (SSDs): partitioning, formatting, defragmentation… 


The content of the article

  • 1 An increase in the volume of the disk ‘C:’
    • 1.1STEP 1: Open disk management
    • 1.2STEP 2: we separate some of the free space
    • 1.3 STEP 3: attach to disk ‘C:’ not a distributed location
    • 1.4A, what if the expand volume tab on disk ‘C:’ not active
      • 1.4.1 Option 1: using alternative software
      • 1.4.2 Option 2: by deleting the ‘failed’ section

Increasing the volume of the disk ‘C:’

(Relevant for Windows 7, 8, 10, 11. Without data loss and additional programs)


STEP 1: Open disk management

Modern Windows OS has a built-in service program for formatting and splitting disks. It is called -

To do this, press the button combination. Win R

Next, a window should appear’Run’- enter in the line’Open the diskmgmt.msc command.

diskmgmt.msc - start disk management

Then the desired utility should start…

Disk management


STEP 2: We separate some of the free space

Now we need to select the disk partition on which there is free space, and ‘take away’ it for later joining to the disk partition ‘C:’.

  • ‘C:’ - for 132 GB (see the screenshot below
  • ‘H:’ - on 751 GB (on which 187 GB is free, and I will give part of this space to the ‘C:’ section).

To do this, right-click on the ‘H’ section:’ and select an option’Compress the volume’ (I note that the data should not be affected!).

Compress the volume

Then Windows will think for a minute or two: an analysis of free disk space will be performed to assess the possibility of compression.

Waiting - disk analysis

Now you need to specify how much free space you want to take away on the disk. In my example below, I took the figure of 5000 MB (i.e. 5 GB).

How much free space to take away in MB

After the partition is compressed - You should see how you have a not a distributed location

Not a distributed area


STEP 3: Attach to disk ‘C:’ not a distributed location

Right-click on the disk to which we want to attach an unallocated disk space (in the current example, attach to disk ‘C:’), and select the option ‘Expand volume’ in the menu.

If you have the option ‘Expand volume’ is not active and is gray (it cannot be pressed) - read the article below a pair of proposed solutions

Expanding the volume (disk C)

Next, you will be offered to attach an unmarked area on the disk (the 5 GB that we took away from another disk partition in the previous step). Select them and click next.

Volume Expansion Wizard

In general, the last step is to agree to the operation by clicking on the ‘Done’.


That’s it! Now your system disk has grown by 5000 MB.


And what if the expand volume tab on the ‘C’ drive:’ not active

In some cases, when trying to expand a volume, this option in disk management may not be active (it just turns gray and cannot be clicked, example below).

Expand volume is not active

There are two solutions:

  1. The easiest option in this case is to use special programs to change the size of HDD partitions
  2. You can also try to delete the extra partitions used for recovery (usually, it’s all because of them). As a rule, this is observed more often on laptops, where there are special sections from the manufacturer. In my example below, I’ll show you how to remove them so that the ‘Expand Volume’ function becomes active (Important


Option 1: Using alternative software

And so, we will assume that the MiniTool Partition Wizard utility is installed and running.

1) First you need to find the disk partition that you want to attach (in my example

To confirm the action, click the ‘Apply’ button in the upper left corner.

Selecting and deleting the partition we want to attach (it is empty)

The status of this section should become ‘Unallocated’ (see the screenshot below).


2) Next, you need to right-click on the system disk ‘C:’(i.e., to which we will attach an unmarked area) - and choose the ‘Extend’ option.

Extend - extend the disk with the OS

3) A window will appear in which you need to select our unmarked area (in my case, those 25 GB), move the slider to the right to the maximum and click ‘OK’.

For the entire amount of free space

4) After that you should see that the unmarked area will be attached to the ‘C’ disk:’ (see the screenshot below

Now only the OS section

Note: In some cases, you may need to restart your computer to perform the operation…


Option 2: by deleting the ‘failed’ section

You must first run

CMD as administrator

  • enter the command diskpart
  • then the commandlist disk
  • select disk 0


Next steps:

  • list partition
  • select partition 6

List partition (in my case, it was necessary to delete the 6 and 8 partitions (used for recovery) in order for the ‘Expand Volume’ tab to become active).

And the last command to delete the selected section is delete partition override

Important!Be careful, this command will delete the selected section, all information from it will disappear!

The selected section has been deleted!

To delete the next partition, you need to select it again (for example, select partition 8, and then use the delete partition override command again).


Actually, that’s all - the problem is solved!

Good luck!

First publication: 8.06.2017 

Adjustment: 1.02.2022

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