How to Use and Allocate Unallocated Space in Windows 10 [6+ Ways]

Daisy updated on Sep 04, 2020 to Partition Master | How-to Articles

disk management unallocated space

What Is Unallocated Space

Unallocated space, as the name suggests, is part of disk space that is not allocated to any partition. A computer describes any physical space on a hard drive that doesn't belong to a partition as unallocated. This means that no programs can write data to this space, nor save data until it's being a part of the real disk partitions.

You won't see unallocated space in Windows Explorer, only find that a hard drive is showing less space than actual, for example, 1TB shows 700GB. Fortunately, you can view the whole disk space allocation state, including unallocated space in Disk Management on Windows 10/8/7 computers.

On this page, we'll take allocating unallocated space on Windows 10  as an example to guide you to make use of unallocated space on a hard drive, external hard drive, and other storage devices:

What To Do with Unallocated Space
How to Use and Allocate Unallocated Space in Windows 10
Bonus Tip: Fix Unallocated Space in Windows 10 Can't Use Error

What To Do with Unallocated Space

Before starting to use unallocated space, you will need to know what to do or what you can do with the unallocated space. Basically, there are two things that you can do as listed here:

  1. [1]. Create a new partition
  2. [2]. Extend an existing partition

If you need a new location for saving some specific files or data, you can create a new partition with the unallocated space. If your C drive or other data partitions are having a low disk space issue, you can extend an existing partition.

How to Use and Allocate Unallocated Space in Windows 10

Applies to: Choose the right tools and allocate unallocated space on Windows 10/8/7 disks.

Either you want to create a new partition or extend a partition with the unallocated space, you'll need to choose a handy tool for help. In this part, we included 3 tools with detailed tutorial steps to help you out.

Let's start with the tutorial steps below to make use of unallocated space on your hard drive or external hard drive:

1. To Create a New Partition with Unallocated Space

Applies to: create more than one partition on a hard disk, and create a partition on an external storage device for data storage.

Here are three tools that can be applied to make use of unallocated space on Windows 10/8/7 and even older Windows computers:

#1. EaseUS Partition Master - Easiest, For beginners

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 Windows 10 is supported

  1. #2. Disk Management - Medium, For experienced users
  2. #3. Diskpart CMD - Hard, For professionals

You may now follow the tutorial steps below to create partitions with unallocated space on your disk or external hard drive with ease. The former method is listed, the easier it will be:

#1. Use EaseUS Partition Master - Easiest

It can fully meet all demands of making use of unallocated space in Windows 10/8.1/8/7/XP/Vista. Here is how to create a partition on your own:


Step 1: Launch EaseUS Partition Master

On the main window, right-click on the unallocated space on your hard drive or external storage device and select "Create".

Create partition on unallocated space

Step 2: Adjust the new partition size, file system, label, etc.

Set the size, partition label, drive letter, file system, etc. for the new partition and click "OK" to continue.

Set up new partition

Step 3: Confirm to create a new partition

Click on the "Execute Operation" button and confirm to create a new partition by clicking "Apply".

Confirm and keep all changes

The following video guide also shows how to create, delete, and resize partition on Windows computer.

#2. Use Disk Management - Medium

It's an optimal way to manage the unallocated space using Windows 10 Disk Management. Here are the steps to create a new partition:

Step 1: Right-click Windows icon and select Disk Management.

Step 2: Locate and right-click on unallocated space in Disk Management, select "New Simple Volume".

Create a new partition

Step 3: Specify the partition size and click "Next" to continue.

Step 4: Set a drive letter, file system - NTFS, and other settings to the new partitions. Click "Finish" to complete creating a new partition.

Finish creating new partitions.

#3. Use DiskPart CMD Command - Hard

Step 1: Open DiskPart command prompt:

Type cmd in Search > Right-click Command Prompt > "Open as Administraor" > Type diskpart and hit Enter.

Step 2: Type the following command and hit Enter each time:

  • list disk
  • select disk 0 (Replce 0 with your disk number)
  • create partition primary size=x or create partition logical size=x (replace x with partition size in MB)
  • a ssign letter=H (Replace H with a new partition drive letter)
  • format fs=ntfs quick

create new partition on unallocated space using diskpart

Step 3: Type exit to close DiskPart.

If you need to create more than one partition with the unallocated disk space, repeat the above steps with the chosen tool.

2. Extend an Existing Partition Using Unallocated Space

You may also use the following three tools to extend partition with existing unallocated space on your disk:

  1. #1. Use EaseUS Partition Master
  2. #2. Use Disk Management
  3. #3. Use DiskPart CMD Command

Applies to: Adding unallocated space to an existing partition is ideal to fully utilize the free space, meanwhile, solve the low disk space warning on the target partition.

#1. Use EaseUS Partition Master - Beginners 1st Choice

EaseUS Partition Master allows users to drag and move unallocated space to anywhere they like. Let's see how to flexibly extend a partition even the unallocated space is not adjacent:

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 Windows 10 is supported

Step 1. Right-click the target partition that you want to extend with unallocated space, select "Resize/Move".

resize unallocated space

Step 2. Drag one side of the target partition to the right or left so as to add unallocated space into the current partition.

resize unallocated space 2

With the Resize/Move feature, you can directly add unallocated space to any partition without moving its position at all.

Step 3. Click "OK". Click "Execute Operation", and it will execute the operations to add the unallocated space into the target partition eventually.

resize unallocated space 5

#2. Use Disk Management - For experienced users

Step 1: Open Disk Management by right-clicking on Windows icon and select "Disk Management".

Step 2: Right-click on the partition that you want to extend and select "Extend Volume".

Extend partition using unallocated space.

Step 3: Click "Next" to continue, adjust the size of unallocated space to add to the selected partition.

Step 4: Click "Next" and "Finish" to complete the process.

Extend volume using unallocated space

#3. Usk DiskPart Command - For professionals

Step 1: Open DiskPart command prompt:

Type CMD in Search > Right-click Command Prompt > Select "Run as Administrator" > Type diskpart and hit Enter.

Step 2: Type the following command links and hit Enter each time:

  • list disk
  • select disk 0 (replace 0 with your disk number)
  • list volume
  • select volume x (replace x with the target partition number that you want to extend)
  • extend size=number (adjust and add unallocated space to the selected volume in MB)
Click to copy

Step 3: Type exit to close DiskPart.

Bonus Tip: Fix Unallocated Space in Windows 10 Can't Use Error

Applies to: Fix unallocated space in Windows 10 or Windows 8/7 computer cannot be used error.

If you cannot create or extend partition using the unallocated space, don't worry. Follow through the guidelines here, you'll make full use of the unallocated space on your disk:

1st. Check Disk Capacity - Larger or Smaller than 2TB

Step 1: Open Windows Disk Management.

Step 2: Check the total disk capacity:

If the disk is larger than 2TB, continue with Step 3.

Step 3: Right-click the disk and select "Properties".

If the disk is with MBR, convert it to GPT as guided in the 2nd tutorial.

If your disk is smaller than 2TB but you cannot use the unallocated space in Disk Management with "Extend Volume greyed out" or "New Simple Volume greyed out" error, let EaseUS Partition Master help. You can directly revet to the above tutorials to create a partition or extend partition using EaseUS partition manager.

2nd. Convert MBR to GPT

If your disk is larger than 2TB and it's with MBR, convert it to GPT using EaseUS Partition Master:

Run EaseUS Partition Master > Right-click target disk > Select "Convert to GPT" > Execute Operation.

Step-by-Step Tutorial: How to Convert MBR to GPT

After this, you can then continue with the above steps, you'll be able to allocate the unallocated space again.


On this page, we covered 6 ways to help Windows users to allocate unallocated disk space on Windows 10/8/7 using EaseUS Partition Master, Disk Management, and DiskPart.

You can either create a new partition or extend existing partitions to make use of the unallocated space on your disk. Compared to Disk Management and DiskPart, EaseUS Partition Master is exclusively designed for Windows OS and Windows Server users to manage their hard disks and partitions.

It's much easier to handle, and most of all, smarter than any native Windows disk management and DiskPart.

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 Windows 10 is supported

People Also Ask About Unallocated Space

For further questions and answers related to unallocated space on Windows 10 or even older Windows systems, check the answers below. You may get a satisfying answer:

1. Where does unallocated space come from?

Where does unallocated space come from? Generally, unallocated space is generated by manufacturers as a default space state on storage devices, especially on the hard drive and SSD disk. You can also get unallocated space when you delete a partition or you shrank a partition.

2. What to do if Disk Management option greyed out on unallocated space?

Don't worry when you cannot allocate unallocated space with Windows disk management as its "Extend Volume" and "New Simple Volume" options are greyed out.

Here are two ways to help you out:

  1. [1]. Use EaseUS Partition Master and continue allocating the unallocated space;
  2. [2]. Convert the hard disk with unallocated space to GPT and retry again.

3. Can't extend C drive without unallocated space?

When there is no unallocated space on your hard drive, you may not be able to extend C drive using Disk Management. You must delete or shrink partition next to C drive so as to free up space.

EaseUS Partition Maser offers another option for you that you can allocate free space from other partitions to your C drive with its Allocate Space feature. Or, you can also use its Resize/Move feature to flexibly move free space to C drive.

Check: Move Space from D Drive to C Drive, or Transfer Disk Space from One Partition to Another.

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Frequently Asked Questions

Why Choose EaseUS Partition Master?

"I've used Partition Master Professional many times to create, delete, format, move, rename, and resize partitions."PCWorld

"Partitioning tools have come a very long since the days of complicated command line utilities and EASEUS Partition Master is one of the most advanced programs available."TECH ADVISOR

"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."Lifewire

Will the "Migrate OS" feature transfer the Windows system files only or the whole C drive?

To ensure that the migrated system will boot normally, the Migrate OS feature will transfer all the files in the system and the boot partitions. Generally, the boot partition is the C drive so the transfer will include all the files in C.

Does EaseUS Partition Master license apply to multiple computers?

The license of Partition Master Professional and Server editions can be used on 1 computer only, while that for for the Technician and Unlimited editions can be used on multiple machines.

What is the difference between EaseUS Partition Master Trial version and the Free version?

Free is for home users only, with most basic functions available such as partition resize and clone. While trial can help you understand how this product works and test what a full license can do on a business or server OS machine.

Will it cause any data loss after resizing the partition in EaseUS Partition Master?

Generally, it will not cause any data loss or boot issue by resizing a partition. However, in order to protect your data, we suggest that you backup the partition before resizing, in case of any unexpected situations such as power outages, computer hardware failures, etc. You can use EaseUS Todo Backup to backup the partition and its trial version is fully functioned for 30 days.

What should I prepare before resizing the partition?

On the partition that is going to be operated, there might be some files being occupied by other programs. To ensure a successful operation, we suggest that you close all the unnecessary software before resizing that partition. Otherwise, EaseUS Partition Master will detect the partition being locked by the other software and require a reboot to resize the partition under boot mode.

About EaseUS Partition Master

All-round disk & partition management software for personal and commercial use. Let it manage your storage drive: resize, format, delete, clone, convert, etc.

Video Tutorial

How to Partititon a Hard Drive on Windows 10/8/7