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How to Extend C Drive in Windows 10 Without Formatting

Updated by Tracy King on Oct 19, 2021
Written by Daisy
mins read

Have you ever receive the low disk space warning when you boot your computer or use a hard drive? When this error message pops out, it means that your hard drive is running out of space.

C drive low disk space

Insufficient disk space will affect the normal use of a computer, the system disk space shortage is particularly serious. When your C drive is full and out of space, you will suffer low work efficiency, the system will run unstable, and you may not be able to download and install new software or use the installed programs.

If you are in this situation, don't worry. One way to solve this problem is to extend system partition to improve computer performance. How to extend C drive in Windows 10/8/7? EaseUS partition manager offers you the simplest way to increase C drive.

How to Extend C Drive with EaseUS Partition Master

EaseUS Partition Master is an all-in-one partitioning tool that is fully compatible with Windows 10/8.1/8/7/Vista/XP. With this program, you can extend C drive effortlessly with or without unallocated space.

When there is unallocated space on your system disk, you can simply resize C drive to get more space. When there is no unallocated space on your hard disk, you can apply EaseUS partition manager to increase C drive with free space on other partitions. 

You can make the following hard drive managements without data loss and any effort with EaseUS disk management tool. 

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1. Extend C Drive Automatically in 1-Click with Smart Space Adjustment Feature

EaseUS Partition Master has the "Adjust with 1-Click" function to extend a drive that is out of space automatically. When your C drive is out of space, you will see the low disk space alert on the software interface. Then, with only a few clicks, you can resize and expand your C drive without any data loss.

Step 1. Click "Adjust with 1-Click" to extend C drive.

When your C drive is out of space, you will see the Low Disk Space alert on EaseUS Partition Master. Click the Adjust button to extend it.

How to Adjust Low C Drive Space Step 1

Step 2. Click "OK" to extend C drive automatically.

By clicking "OK", EaseUS Partition Master will automatically allocate space to your C drive to solve the low space issue.

How to Adjust Low C Drive Space Step 2

Extra Option: You can also click "Manual Adjustment" to extend the C drive manually.

When turning to Manual Adjustment, select the C drive, and drag dots rightward to add more space to C drive. Click "OK" to confirm.

Manually Adjust Low C Drive Space

Step 3. Confirm to resolve low disk space in C drive

Click the "Execute Operation" button at the top corner and start all pending operations by clicking "Apply".

How to Adjust Low C Drive Space Step 3

If you want to manually expand your C drive, you can use the Allocate Space option of EaseUS Partition Master to move space from D drive to C drive or transfer free space from any other available drive to the system drive.

2. Extend C Drive Without Formatting Using Resize/Move Partition Option

When there is no unallocated space on your disk and you don't want to delete or format the hard drive, you can use EaseUS partition management software to extend C drive and by its "Resize/Move partition" feature.

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Option 1. Extend System C drive with unallocated space

  1. 1. Right-click on the System C: drive and select "Resize/Move".
  2. 2. Drag the system partition end into the unallocated space so to add it to the C: drive. And click "OK". 
  3. 3. Click "Execute Operation" and "Apply" to execute the operations and extend the C drive.

Option 2. Extend System C drive without unallocated space

  1. 1. Right-click a big partition with enough free space on the system disk, select "Allocate Space".
  2. 2. Select the system drive at the Allocate Space From (*) To section, and drag the end of System C drive into the unallocated space. Click "OK" to confirm.
  3. 3. Click "Execute Operation", it will list the pending operations, and click "Apply" to save the changes and extend the C drive.

0:00-0:32 Extend System Drive with Unallocated Space; 0:32-1:00 Extend System Drive without Unallocated Space.

How to Extend C Drive When There Is Adjacent Unallocated Space 

As mentioned before, you can use EaseUS Partition Master to add space to the C drive in complicated circumstances. For example, there is no unallocated space on your disk, or the unallocated space is not adjacent to the C drive.

However, if you are in this simple case, that is C drive has adjacent unallocated space, you have two ways to expand C drive.

1. Extend C Drive by Using Disk Management

Windows 10 Disk Management can finish some basic disk management, such as delete/format/create/shrink a partition. Here are detailed steps for extending the C drive.

If the unallocated space is not adjacent to the C drive on its right side, the Extend Volume will grey out. And you need to apply EaseUS Partition Master to expand C drive.

Step 1. Right-click the Windows button, choose "Disk Management".

start disk management

Step 2. Right-click C drive and choose "Extend Volume...".

extend C drive with disk management

Step 3. Follow the on-screen instructions to finish extending C drive. 

expand C drive

2. Increase C Drive with Diskaprt Utility

When there is a contiguous adjacent unallocated space behind the C drive, you can also increase C drive by using the Diskpart tool in CMD.

Step 1. Press the Win+R buttons to open the Run dialogue. Then, type diskpart and press Enter.

Step 2. Type the following command lines in order and press Enter after each one.  

list disk
select disk x
(x is the number of the system disk)
list partition
select partition x 
(x is the number of C drive)
extend size=x disk=N (x is the size in MB you want to add to the system partition, N is the number of your system disk.)

extend C drive in diskpart

EaseUS Partition Master - A Simple C Drive Partition Extender

After reading this guide, we believe that you've learned how to extend C drive in every way. If there is adjacent unallocated space right behind the C drive, you can use the Windows built-in tools - Disk Management and Diskpart to extend C drive with ease.

If things get a little more complicated, then, EaseUS Partition Master is your best choice. It can easily extend C drive with different solutions, such as:

  • Extend C drive automatically with "Adjust with 1-Click" feature when it is in low disk space.
  • Allocate space from other partitions to C drive without deleting.
  • Quickly expand C drive even the unallocated space is not adjacent to the system drive.

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About the Author

Updated by Tracy King

Tracy joined in EaseUS in 2013 and has been working with EaseUS content team for over 7 years. Being enthusiastic in computing and technology, she writes tech how-to articles and share technical solutions about Windows & Mac data recovery, file/system backup and recovery, partition management and iOS/Android data recovery.

Read full bio

Written by Daisy

Daisy is the Senior editor of the writing team for EaseUS. She has been working in EaseUS for over ten years, starting from a technical writer to a team leader of the content group. As a professional author for over 10 years, she writes a lot to help people overcome their tech troubles.

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  • I love that the changes you make with EaseUS Partition Master Free aren't immediately applied to the disks. It makes it way easier to play out what will happen after you've made all the changes. I also think the overall look and feel of EaseUS Partition Master Free makes whatever you're doing with your computer's partitions easy.

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  • Partition Master Free can Resize, Move, Merge, Migrate, and Copy disks or partitions; convert to local, change label, defragment, check and explore partition; and much more. A premium upgrade adds free tech support and the ability to resize dynamic volumes.

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  • It won't hot image your drives or align them, but since it's coupled with a partition manager, it allows you do perform many tasks at once, instead of just cloning drives. You can move partitions around, resize them, defragment, and more, along with the other tools you'd expect from a cloning tool.

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