By Emily / Last Updated November 5, 2020

Why partition a hard disk in Windows 10?

Partitioning a hard disk is a process of separating a physical hard disk into several independent drive partitions. You might feel confused about whether it is necessary to do this. Here, we will list some top reasons for that.

▸Better organize your data: After partitioning a hard disk into several separate logical drive partitions, you can organize your data on every partition much more precisely such as one for your operating system, one for your personal data and so on.

▸Run different operating systems on one computer: If you want to run two different operating systems on one computer, having several separate partitions is necessary since every operating system needs an independent partition.

▸Reduce the threats of data loss: If you have different partitions for OS and other personal data, you can keep your personal files safe and minimize the data loss when the operating system crashes and needs a reinstallation.

Partition hard disk without formatting via Disk Management

No matter for what reason to partition a hard disk, you can partition a hard disk via Windows Disk Management, which is a built-in tool of Windows. It is able to shrink volume, extend partition, create partition, format partition. Below is how to shrink a partition and create a partition in Disk Management.

1. Open Disk Management: right-click “This PC”, then click” Manage”->” Storage”->” Disk Management”.

2. Select a partition you want to shrink and choose"Shrink Volume".

Shrink Volume

3. In this pop-out mini window, you can know the total size before shrink, and available unused space you can shrink for a new partition. You can save the default shrink size and directly hit “Shrink”. Or you can specify the size of the eventual partition by inputting it in megabytes in the respective field.

Shrink Size

4. After that, you’ll get an “unallocated” space shown next to the original partition. Right-click the “Unallocated” space and select “New Simple Volume” from the resulting menu, then follow the guidance to create a new partition.

New Volume

To create more partitions on the hard disk, you can repeat the “shrink and create” procedure.

Partition hard disk without formatting via partition software (3 ways)

Apart from using Windows Disk Management, you can also use a third-party disk partition manager like AOMEI Partition Assistant Professional. It works well with all editions of Windows 10/8/7/XP/Vista (both 32-bit and 64-bit). Being more versatile and powerful, it comes with many features that Disk Management does not have, including “Merge Partition”, “Split Partition”, “Move Partition”, “Allocate Free Space from one partition to another” and more.

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If you want to combine two partitions into one or merge unallocated space into an existing partition, the “Merge Partition” function is recommended. On the contrary, if you want to divide a large partition into two smaller ones, you can make use of “Split Partition”. Moreover, if you are partitioning a new hard disk, the "Quick Partition" featue is a perfect method. The following content will show you how to partition hard drive without formatting via those 3 functions:

Method 1. Split a large partition into two smaller partitions

You can only split the unused space of a partition to create a new partition. If a partition is totally used up, the partition will be unable to be split.

1. Install and launch AOMEI Partition Assistant. Right-click the partition which you want to split, select "Split Partition" (ex: C drive).

Split Partition

2. In this window, you can change the original and new partition size by dragging the double-headed arrow leftwards or rightwards. Additionally, you can directly type in the number of the size you want to give to your new/original partition, and click “OK” to continue.

Change Partition Size

Tip: If the partition exists on an SSD, you can tick “Allow partition alignment to optimize the performance of SSD” by clicking “Advanced<<”.

3. Click “Apply” and "Proceed" to confirm the change.


Method 2. Allocate free space from one partition to another

If one partition on the hard disk is almost full while another partition has a lot of free space, “Allocate Free Space” allows you to directly assign free space from one partition to another within 3 steps:

1. Right-click the partition with free space and choose “Allocate Free Space”.

Allocate Free Space

2. Here, you can decide to allocate how much space to which partition. For example, allocate free space from D to C.

Allocate From D To C

3. Click “Apply” to commit the pending operation.

Apply Allocate Free Space

Method 3. Quick partition

Besides, for a new hard disk, you can use another function of AOMEI Partition Assistant Pro-”Quick Partition”, which can partition a hard disk with two clicks.

Quick Partition


As for how to partition hard disk without formatting in Windows 10, you can apply Disk Management or AOMEI Partition Assistant. Both of them could divide a hard disk into separate partitions. AOMEI Partition Assistant is easier-to-use and more advanced. Besides the functions mentioned above, it is also able to clone hard disk, convert MBR and GPT without deleting partitions, convert dynamic to basic disk without losing data and so on. To enjoy those amazing functions on Windows Server, you can check out the Server edition.