WindowsAdvanced

How to Create, Shrink, Extend, and Delete Partitions in Windows 11/10 After Installation – Complete Disk Management Guide

A very common situation occurs when Windows is installed on a new laptop or desktop and the installer uses almost the entire SSD or hard disk as the C: drive...

Bison Technical Team Enterprise IT specialists

Updated 29 Aug 2026 18 min read 0 total views

A very common situation occurs when Windows is installed on a new laptop or desktop and the installer uses almost the entire SSD or hard disk as the C: drive.

For example, you purchase a computer with a 1 TB SSD, but after Windows installation you see something similar to:

C: Drive – approximately 930 GB

You may prefer to keep Windows and applications on C: while storing documents, accounts, backups, photographs, or business data on another partition such as D:.

The good news is that you normally do not need to reinstall Windows or format the entire computer.

Windows includes a built-in utility called Disk Management that can shrink an existing partition and use the released space to create another partition. Disk Management in Windows 10 and Windows 11 supports common operations including creating, formatting, shrinking, extending, and deleting volumes.

This article explains these operations from an end-user perspective:

Shrink Volume – Make an existing partition smaller.

New Simple Volume – Create a new drive/partition from unallocated space.

Extend Volume – Add available unallocated space to an existing partition.

Delete Volume – Delete a partition and convert its space into unallocated space.

Before You Start – Important Safety Information

Partition management modifies the structure of your storage device. Although Windows Disk Management is designed to perform supported resize operations without requiring the partition to be reformatted, you should always have a backup of important data before changing partitions.

Recommended precautions

Before proceeding:

Back up important documents.
Save and close all applications.
Make sure the computer has stable power.
Connect a laptop to its charger.
Check that the drive does not have hardware or file-system problems.
Make sure you are modifying the correct disk and partition.
If BitLocker/device encryption is enabled, make sure you have access to the recovery key before making significant disk or boot-related changes.

Very Important

Do not randomly delete small partitions that do not have drive letters.

Modern Windows computers commonly contain partitions such as:

EFI System Partition
Recovery Partition
OEM Recovery Partition
Windows C: partition

These small partitions may be required for Windows startup, recovery, or manufacturer recovery functions.

If you do not recognize a partition, do not delete it just because it appears unused.

Understanding Disk Management

Windows Disk Management is the built-in graphical utility used to manage physical disks, partitions, and volumes.

Microsoft documents Disk Management for both Windows 10 and Windows 11 and notes that it can create and format volumes, change drive letters, and extend or shrink existing volumes.

How to Open Disk Management

Method 1 – Using the Start Button

Right-click the Start button.

Select:

Disk Management

Method 2 – Using Run

Press:

Windows Key + R

Type:

diskmgmt.msc

Press Enter.

Method 3 – Windows Search

Search for:

Create and format hard disk partitions

Open the matching result.

Understanding What You See in Disk Management

You may see something similar to:

Disk 0

Partition	Approximate Size	Purpose
EFI System Partition	100–300 MB	Windows boot files
C:	930 GB	Windows, applications and data
Recovery Partition	500 MB–several GB	Windows/OEM recovery

The exact layout differs from computer to computer.

If almost the entire usable SSD is assigned to C:, you cannot immediately create D: because there is no Unallocated space.

You must first create unallocated space.

That is what Shrink Volume does.

Part 1 – How to Shrink C: Drive and Create Another Partition

Consider this example:

You have:

C: = 930 GB

You want approximately:

C: = 630 GB
D: = 300 GB

You can shrink C: by approximately 300 GB and use the resulting unallocated space for D:.

Step 1 – Check Free Space on C:

Open:

File Explorer → This PC

Check the amount of free space available on C:.

Do not shrink C: so aggressively that Windows has little free space left.

Windows requires free storage for:

Windows Updates
Temporary files
Application installation
Page file
System Restore
Browser caches
User profiles
Feature updates
Application data

As a practical rule, leave comfortable free space on C: rather than trying to make the Windows partition as small as possible.

Step 2 – Open Disk Management

Press:

Windows + R

Type:

diskmgmt.msc

Press Enter.

Locate the C: partition carefully.

Step 3 – Select Shrink Volume

Right-click:

Select:

Shrink Volume

Windows will display:

Querying volume for available shrink space, please wait...

This can take some time.

Windows then displays the Shrink dialog box.

Step 4 – Understand the Shrink Volume Screen

You will normally see fields similar to:

Total size before shrink in MB

Size of available shrink space in MB

Enter the amount of space to shrink in MB

Total size after shrink in MB

The important field is:

Enter the amount of space to shrink in MB

This represents approximately how large the space released from C: will be.

GB to MB Calculation for Shrink Volume

Disk Management asks for the shrink amount in MB, not GB.

For practical partition calculations:

1 GB = 1024 MB

Therefore:

Desired Space	Enter Approximately
20 GB	20,480 MB
50 GB	51,200 MB
100 GB	102,400 MB
150 GB	153,600 MB
200 GB	204,800 MB
250 GB	256,000 MB
300 GB	307,200 MB
400 GB	409,600 MB
500 GB	512,000 MB

For example, if you want to create approximately a 300 GB D: drive, enter:

307200

Then click:

Shrink

What Happens After Shrinking C:?

Windows reduces the size of C:.

The newly released space appears in Disk Management as:

Unallocated

usually represented with a black bar.

For example:

C: 630 GB | 300 GB Unallocated

Your new D: drive does not exist yet.

You must now create a volume using this unallocated space.

Microsoft explains that shrinking creates new unallocated space from the end of the volume and ordinary files are automatically relocated where possible; no reformat is required for the supported shrink operation.

Part 2 – How to Create D: Drive from Unallocated Space

Once you have unallocated space:

Right-click the area showing:

Unallocated

Select:

New Simple Volume

The New Simple Volume Wizard opens. Microsoft documents this same workflow for creating a new partition from unallocated disk space.

Click:

Next

Step 1 – Specify Volume Size

Windows asks:

Simple volume size in MB

If you want to use all the available unallocated space for D:, leave the default maximum value.

Click:

Next

Step 2 – Assign a Drive Letter

Select:

Assign the following drive letter

For example:

If D: is already being used by a DVD drive or another device, select another available letter such as:

E: or F:

Click:

Next

Step 3 – Format the New Partition

For a normal internal Windows data partition, you can generally select:

File system: NTFS

Allocation unit size: Default

Volume label: Data

Enable:

Perform a quick format

Then click:

Next → Finish

After a short time, the new partition appears in File Explorer.

You now have something similar to:

Windows (C:)

and

Data (D:)

You have successfully created another partition without reinstalling Windows.

Can I Create More Than One Partition?

Yes.

Suppose you shrink C: by approximately 500 GB.

Instead of making one 500 GB D: partition, you could create:

D: – 300 GB

and

E: – 200 GB

Simply specify a smaller size when creating the first New Simple Volume.

The remaining space will stay unallocated, and you can create another volume from it.

Part 3 – What Is Shrink Volume?

Shrink Volume reduces the allocated size of an existing volume and creates unallocated disk space.

Example before shrinking:

C: 930 GB

After shrinking C: by 300 GB:

C: 630 GB | Unallocated: 300 GB

You can then use that unallocated space to create D:.

Does Shrink Volume Delete Files?

Under normal supported conditions, shrinking an NTFS partition with Windows Disk Management does not require deleting your existing files. Windows relocates ordinary files where possible while shrinking the volume.

However, backup is still strongly recommended because any disk-management operation carries some risk from power failure, disk problems, human error, or unexpected system issues.

Why Can't Windows Shrink C: as Much as I Want?

This confuses many users.

Imagine:

C: capacity = 1 TB

Used space = 200 GB

Free space = 700+ GB

You may expect Windows to allow C: to shrink by 600 GB.

Instead, Disk Management may allow only 100 GB.

Why?

Windows can encounter unmovable files near the end of the partition.

Microsoft specifically notes that files such as the paging file or shadow-copy storage can prevent the partition from shrinking beyond their location.

Examples may include:

Page file
Shadow copies
Certain system metadata
System protection data

Therefore:

Free space shown in File Explorer does not necessarily equal the maximum shrinkable space.

This is normal.

Part 4 – What Is Extend Volume?

Extend Volume performs the opposite operation.

Instead of making a partition smaller, it makes the partition larger by adding suitable unallocated disk space.

Example:

Before:

D: 200 GB | Unallocated 100 GB

After extending D::

D: 300 GB

How to Extend a Partition

Open:

Disk Management

Right-click the partition you want to increase.

For example:

Select:

Extend Volume

Click:

Next

Choose how much available space you want to add.

Click:

Next → Finish

The volume becomes larger.

Microsoft's current guidance states that Disk Management requires suitable unallocated space on the same physical disk and, for a basic volume, that space needs to be immediately after the volume being extended.

Why Is Extend Volume Greyed Out?

This is one of the most common Disk Management questions.

Suppose your disk looks like:

C: | D: | Unallocated

You right-click C:, but:

Extend Volume

is greyed out.

Why?

Because D: is located between C: and the unallocated space.

For the normal Disk Management extension of a basic partition, Windows requires the unallocated space to be immediately to the right of the partition you want to extend.

So this works:

C: | Unallocated

But this does not allow C: to be extended directly:

C: | D: | Unallocated

because D: sits between C: and the free space.

Important Example – Shrinking D: Does Not Necessarily Let You Extend C:

Suppose your disk is:

C: 300 GB | D: 600 GB

You need another 100 GB for C:.

You shrink D: by 100 GB.

The result is normally:

C: 300 GB | D: 500 GB | Unallocated 100 GB

You still cannot extend C: using Disk Management because D: remains between C: and the unallocated space.

This is a very important limitation to understand.

How Can I Extend C: in That Situation?

One possible built-in method is:

Back up everything from D:.
Delete D:.
The space becomes unallocated next to C:.
Extend C: by the required amount.
Create D: again from the remaining unallocated space.
Restore your data to D:.

For example:

Before:

C: 300 GB | D: 600 GB

After deleting D::

C: 300 GB | Unallocated 600 GB

Extend C: by 100 GB:

C: 400 GB | Unallocated 500 GB

Create D: again:

C: 400 GB | D: 500 GB

WARNING

Deleting D: destroys the data stored on D:.

Back up everything first.

Another approach is to use a reputable third-party partition manager capable of moving partitions, but such operations should also be preceded by a verified backup.

Part 5 – What Is Delete Volume?

Delete Volume completely removes a selected data volume and converts its storage into Unallocated space.

Example:

Before:

C: 400 GB | D: 500 GB

Delete D:.

After:

C: 400 GB | Unallocated 500 GB

The files previously stored on D: are no longer available through that partition.

Microsoft warns that deleting a partition or logical drive deletes both the partition and the data stored on it.

How to Delete a Volume

WARNING: THIS DELETES DATA

Before continuing, copy all required files from the partition to another drive or backup location.

Then:

Open Disk Management.
Find the correct partition.
Right-click it.
Select Delete Volume.
Read the warning carefully.
Confirm the deletion.

The partition becomes:

Unallocated

You can then:

Create a new partition from it
Extend an adjacent compatible partition
Leave it unallocated temporarily

Never Delete a Partition Just Because It Has No Drive Letter

This deserves special attention.

You might see something like:

260 MB EFI System Partition

C: 475 GB

900 MB Recovery Partition

The small partitions are not necessarily useless.

Do not delete:

EFI System Partition

System Reserved

Windows Recovery Partition

OEM Recovery Partition

unless you fully understand the computer's boot/recovery configuration and specifically intend to change it.

Deleting the wrong system partition can cause Windows startup or recovery problems.

Difference Between Shrink, Extend, Delete, and Format

Operation	What It Does	Normally Keeps Existing Files?
Shrink Volume	Makes a partition smaller	Yes
Extend Volume	Makes a partition larger	Yes
Delete Volume	Removes the entire volume	No
Format Volume	Creates a new file system	No – treat existing data as lost
New Simple Volume	Creates a partition from unallocated space	N/A

Understanding this table can prevent serious mistakes.

Example: 512 GB SSD with Only C: Drive

Suppose your new laptop has a 512 GB SSD.

After Windows installation you see approximately:

C: 475 GB

You want:

C: approximately 275 GB

D: approximately 200 GB

Open Disk Management.

Right-click C:.

Select:

Shrink Volume

Enter approximately:

204800 MB

Click:

Shrink

You now have approximately:

200 GB Unallocated

Right-click it.

Select:

New Simple Volume

Assign:

Format as:

NTFS

Name it:

Data

Your computer now has separate C: and D: partitions.

Example: 1 TB SSD with Only C: Drive

Suppose Windows shows approximately 930 GB usable capacity.

You want approximately:

C: 430 GB

D: 500 GB

You could attempt to shrink C: by approximately:

512000 MB

If Windows reports that the maximum available shrink space is smaller than this, use the maximum Windows permits or investigate the unmovable files preventing further shrinkage.

Do not force partition changes without understanding why Windows is limiting the operation.

Should Windows and Personal Data Be Kept on Separate Partitions?

It is often convenient, but it is not mandatory.

A common layout is:

C: – Windows and applications

D: – Documents and business data

Possible benefits include:

Easier organization
Easier identification of user data
Cleaner Windows partition
More convenient data management during some Windows reinstall scenarios

However, there is an important misconception:

D: is not automatically a backup simply because it is a different partition.

If C: and D: are on the same physical SSD and that SSD fails, both partitions can be lost.

Important files should still be backed up to another physical disk, NAS, server, or reputable cloud-backup system.

SSD vs HDD – Is the Procedure Different?

For normal Disk Management operations, the process is essentially the same whether the storage device is:

SATA HDD
SATA SSD
NVMe SSD

You still use:

Disk Management → Shrink Volume → Unallocated → New Simple Volume

What Does Unallocated Space Mean?

Unallocated space is storage capacity on a physical disk that currently does not belong to a usable volume.

It normally does not appear in This PC because it does not yet have a formatted volume and drive letter.

For example:

Disk 0

C: 500 GB | Unallocated 400 GB

The 400 GB physically exists, but Windows File Explorer will not show it as a normal drive until you create a volume from it.

Right-click:

Unallocated → New Simple Volume

to make it usable.

Why Doesn't My New Partition Appear in This PC?

Check Disk Management.

Possible reasons include:

No drive letter is assigned
The space is still unallocated
The volume has not been formatted
The file system is unsupported or damaged
The disk is offline

For a newly created Windows data volume, ensure it has a drive letter such as D: and is normally formatted as NTFS.

What File System Should I Choose?

For a normal internal Windows partition, NTFS is usually the appropriate choice.

For example:

File System: NTFS
Allocation Unit Size: Default
Volume Label: Data
Perform a quick format: Enabled

Microsoft also uses NTFS as the usual file-system choice in its Disk Management guidance for preparing new Windows volumes.

GPT vs MBR – Do I Need to Change Anything?

Usually, no.

Modern Windows systems typically use:

GPT – GUID Partition Table

especially when Windows boots in UEFI mode.

Microsoft describes GPT as the normal choice for modern computers and notes that it supports volumes larger than 2 TB, while MBR is the older partitioning style.

Do not convert GPT to MBR merely because you want to create D:.

Shrinking C: and creating another partition normally does not require changing the disk's partition style.

Common Mistakes to Avoid

Mistake 1 – Deleting C: instead of shrinking it

Never delete your Windows partition simply to create D:.

Use:

Shrink Volume

Mistake 2 – Deleting the EFI partition

This can make Windows unbootable.

Mistake 3 – Deleting the Recovery partition

This may remove Windows recovery capabilities.

Mistake 4 – Assuming Delete Volume is reversible

Treat Delete Volume as a destructive operation.

Back up first.

Mistake 5 – Assuming another partition is a backup

C: and D: on the same SSD still depend on the same physical storage device.

Mistake 6 – Making C: too small

Windows, applications, updates, temporary files, and user profiles all need space.

Leave sufficient capacity for future use.

Mistake 7 – Interrupting the computer during disk operations

Avoid shutting down, restarting, or disconnecting power while disk-management operations are running.

Quick Reference Guide

I have only C: and want D:

Use:

C: → Shrink Volume → Unallocated → New Simple Volume → D:

I want to make D: smaller

Use:

D: → Shrink Volume

I want to make D: larger

You need suitable adjacent unallocated space.

Then use:

D: → Extend Volume

I want to completely remove D:

First back up D:.

Then:

D: → Delete Volume

I want to make C: larger

You generally need compatible unallocated space immediately after C: for Windows Disk Management to extend it.

Frequently Asked Questions (FAQ)

1. Can I create D: after Windows has already been installed?

Yes. If the entire disk is assigned to C:, you can normally shrink C: using Disk Management and create D: from the resulting unallocated space.

2. Do I need to reinstall Windows to create another partition?

No. Windows Disk Management can normally resize an existing NTFS partition and create another volume without reinstalling Windows.

3. Will shrinking C: delete my files?

A normal supported shrink operation is designed to preserve existing files. Windows relocates movable files as necessary.

However, always back up important data before modifying partitions.

4. What is Shrink Volume?

Shrink Volume reduces the size of an existing partition and converts the released capacity into unallocated space.

5. What is Extend Volume?

Extend Volume increases the size of an existing partition by adding suitable unallocated space.

6. What is Delete Volume?

Delete Volume removes the selected volume and its data, leaving its capacity as unallocated space.

7. What is unallocated space?

It is disk capacity that is not currently assigned to a usable partition or volume.

8. Why doesn't unallocated space appear in This PC?

Because it does not yet have a usable formatted volume and drive letter.

Create a New Simple Volume from it.

9. Why is Extend Volume greyed out?

A common reason is that the unallocated space is not immediately after the volume you want to extend. Disk Management has specific adjacency requirements for extending basic volumes.

10. Why can I shrink only 50 GB when I have 300 GB free?

Unmovable system files may be located farther into the partition. Windows cannot shrink the volume beyond their location.

11. Can I create D: from C: without formatting the computer?

Yes. That is one of the most common uses of Shrink Volume.

12. Should I use NTFS for D:?

For a normal internal Windows data partition, NTFS is generally the appropriate choice.

13. Can I create E: as well as D:?

Yes. Create multiple volumes from available unallocated space.

14. Can I delete D: and add all its space to C:?

Potentially yes, provided the resulting unallocated space is positioned correctly for C: to be extended. Back up everything on D: before deleting it.

15. Does deleting D: delete the files inside it?

Yes. Treat Delete Volume as destructive. Microsoft explicitly warns that deleting a volume deletes the data stored on it.

16. Can I delete the Recovery partition?

Ordinary users should not delete Windows/OEM recovery partitions simply to recover a small amount of disk space.

17. Can I delete the EFI System Partition?

No, not during normal partition management. It normally contains boot-related information required by UEFI Windows installations.

18. Is D: safer than C:?

It can make data organization easier, but it is not inherently a backup. If both partitions are on the same failed SSD, both can be lost.

19. Can I partition an SSD?

Yes. Windows can create multiple partitions on SSDs, including NVMe SSDs.

20. Can I shrink C: while Windows is running?

Yes. Windows Disk Management supports shrinking an eligible NTFS system volume while Windows is running.

21. How do I open Disk Management quickly?

Press:

Windows + R

Type:

diskmgmt.msc

and press Enter.

22. How much should I shrink C: to create a 100 GB partition?

Approximately:

102400 MB

23. How much should I shrink for 200 GB?

Approximately:

204800 MB

24. How much should I shrink for 300 GB?

Approximately:

307200 MB

25. Can partitioning improve computer speed?

Simply dividing one physical SSD into C: and D: generally does not provide a meaningful performance improvement. Partitioning is primarily useful for storage organization and management.

26. Can I combine C: and D: again later?

Yes, but the built-in method may require backing up and deleting D: before extending C:, depending on the disk layout. Do not delete D: until its data is safely backed up.

27. Can I extend C: using free space inside D:?

Not directly. Free space inside D: is still part of D:. C: requires suitable unallocated space, and Disk Management normally requires it to be adjacent to C:.

28. Is shrinking a partition the same as deleting it?

No.

Shrink reduces its size while preserving the volume.

Delete removes the entire volume and its data.

29. Is formatting the same as deleting a partition?

No. They are different operations, but both can result in loss of access to existing data. Never format a volume containing files you need.

30. Should I back up before using Disk Management?

Yes. Although normal shrink and extend operations are intended to preserve data, a current backup is strongly recommended before making partition changes.

Conclusion

If Windows was installed using the entire SSD or hard disk as C:, you normally do not need to reinstall Windows simply to create another drive.

The basic process is:

Open Disk Management → Right-click C: → Shrink Volume → Create Unallocated Space → New Simple Volume → Assign D: → Format as NTFS

Remember the four important Disk Management operations:

Shrink Volume = Make a partition smaller

Extend Volume = Make a partition larger

Delete Volume = Remove the partition and its data

New Simple Volume = Create a new partition from unallocated space

For most end users, Shrink Volume followed by New Simple Volume is the safest built-in Windows method for dividing an existing large C: drive into separate C: and D: partitions after Windows has already been installed.

Before deleting, formatting, or making major partition changes, always maintain a verified backup of important data.