How to Extend C Drive in Windows 10 Without Formatting

Updated by

Sherly 

Written by

Daisy 

Updated on Apr 28, 2025

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

Insufficient disk space will affect the normal use of a computer, and 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 Professional 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 management without data loss and any effort with the EaseUS disk management tool. 

Windows 11 users can follow the provided methods on this page for help. You can also refer to this link to get further ideas to extend the c drive in Windows 11.

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 a low disk space alert on the software interface. Then, with only a few clicks, you can resize and expand your C drive without data loss.

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

When your C drive is out of space, hover your mouse over the C drive, you will see the Low Disk Space alert on EaseUS Partition Master. Click "Adjust with 1-Click" to extend it.

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.

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.

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

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

If you want to expand your C drive manually, 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. And don't forget to share this tutorial if you think it's helpful.

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 its "Resize/Move partition" feature.

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 Task" and "Apply" to execute the operations and extend the C drive.

Need a helping hand with these steps? Our customer care team is prepared to offer direct, personalized support to see you through.

EaseUS System Volume or Disk Partitioning Services

Click here to contact EaseUS Partition Master experts for free

EaseUS experts are available to provide you with 1-on-1 manual services (24*7) and help extend C drive or disk partitioning issues. Our experts will offer you FREE evaluation services and efficiently diagnose and resolve low disk space in C drive or other partition problems using their decades of experiences.

• 1. C drive gets full but unable to extend it with unallocated space.
• 2. Extend volume greyed out and unable to increase C drive space.
• 3. To extend C drive with a second disk without losing any data.

How to Extend C Drive When There Is Adjacent Unallocated Space 

As mentioned, 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, 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 basic disk management, such as delete/format/create/shrink a partition. Here are detailed steps for extending the C drive.

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

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

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

Disk Management and the following Diskpart are both reliable disk utilities. Click the buttons below to let more users know about them.

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 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, and N is the number of your system disk.)

Don't forget to share this article with others in need!

EaseUS Partition Master - A Simple C Drive Partition Extender

After reading this guide, we believe 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 the "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.