How to Partition Windows 10 External Hard Drive without Losing Data?

This post shows how to partition Windows 10 external hard drive with built-in tool Disk Management and third-party partition freeware, AOMEI Partition Assistant Professional. Then you can make your external hard drive store data more conveniently.


By Emily / Updated on May 12, 2023

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“How do I partition my Seagate external hard drive Windows 10?”

“Recently, I bought a nice 3TB externala hard drive to store my pictures and other personal files to relieve the burden of the Windows 10 internal hard drive. The drive comes as one large 3 TB partition, but what I want to know is how do I make it into smaller partitions, so perhaps I could designate them for specific uses, like storing pictures in one area, games in another, etc. How do i partition the Windows 10 external hard drive?”

Should you partition Windows 10 external hard drive?

When your Windows 10 system disk is almost running out of space, it is a nice choice to attach an extenral hard drive to store some non-system files. To use a brand-new external hard drive in Windows 10, you have to initialize the hard drive and partiton it first. To better manage your files and find out them quickly when necessary, you should divide the external hard disk into several separately partitions for different types of data storage. Surely, you can also choose to make just one partition.

Initialize New Disk

How to partition Windows 10 external hard drive without losing data?

Now, we will show you how to partition external hard disk in Windows 10 via Windows inbuilt Disk Management and a third-party partition manager.

Method 1. Partition external hard drive via Disk Management

Windows 10 has its partition tool Disk Management. It can help you partition an extenral hard drive within simple clicks. If it is a new disk without any existing partitions on, just one unallocated space, you can take the following steps to divide it into one or more partitions:

1. Type “diskmgmt.msc” in the search box and press “Enter” to open Disk Management tool.

2. In its main interface, find the new external hard drive, right-click the unallocated space and  select “New Simple Volume” to launch the New Simple Volume Wizard. Click “Next”.

New Volume

3. Enter the size of the volume you want to create in megabytes (MB) and select “Next”. If you just need to create one partition on the external hard drive, you can just accept the maximum default size.


4. Accept the default drive letter or choose a different drive letter to identify the partition, and then select “Next”.

Drive Letter

5. Select a file system for this partition and click “Next”.

File System

6. Review your choices and click “Finish”.

This is how to create a partition on a brand new external hard drive. To create more partitions, just right-click the left unallocated space and repeat the steps above. If the external disk has been partitioned into several sections and you want to remove one partition on the external hard drive in Windows 10, you can right-click it, choose “Delete Volume” and follow the instructions.

Please note:
When partitioning an external hard drive in Windows 10, you should pay attention to the partition style (MBR and GPT). The MBR can only support an disk of 2TB at most while GPT disk is free from the limitation. Besides, the MBR external hard drive can support only 3 primary partitions+ 1 extended partitions, or 4 primary partitions while the GPT disk can support 128 primary partitions. Thus, you might meet the following two common problems during partitioning an external hard disk:
1. Cannot create a new partition with unallocated space: that’s because the disk is of MBR but over 2TB. Therefore, even if there is unallocated space, you cannot still create a new partition using it.
2. The newly created partition is a logical drive (not a primary partition): that’s because the external hard drive is of MBR, and has contained 3 primary partitions.
But no need to worry, you can convert MBR to GPT to solve such problems.

Method 2. Partition external hard drive via partition software

To partition an external hard drive more easily, you can also use a 3rd party professional partition manager like AOMEI Partition Assistant Professional. For partitioning a totally new external hard drive with only unallocated space, its “Quick Partition” is a perfect choice, which can partition a hard drive into several sections within two clicks. You can download its demo version for a free trial.

Download DemoWin 11/10/8.1/8/7/XP
Secure Download

Install and launch AOMEI Partition Assistant Professional. Right-click the external hard drive and select “Quick Partition”. In the next window, you can set the partition count, disk type (MBR or GPT), partition size, file system and partition label. When everything is done, click “Start Partitioning”.

Quick Partition

Of cource, if there have been some partitions on the external hard drive, you can also use the professional partition manager to change the partition size or number. Its “Merge Partitions” feature can help merge partitions on the external hard drive: combine two adjacent partitions into one, or merge unallocated space into another partition. You can check out the following steps (merge unallocated space into an existing partitions as an example) to figure out how it works:

Step 1. Right-click the partition you want to extend and select "Advanced" > “Merge Partitions”.

Merge Partition

Step 2. Tick the unallocated space (or an adjacent partition) and click “OK”.

Add Unallocated Space To C Drive

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

Apply Merge

Besides this function, its “Split Partition” can help divide a large partition into two smaller partitions.

C Drive Split

How to make a bootable partition on an external hard drive on Win 10?

Apart from dividing external hard drive into several common data partitions, it is also possible to make a bootable partition on it. Just different intentions requires different methods. Next are 3 most common purposes:

1. Install Windows 10 from external hard drive partition

If you don’t have Windows CD or DVD for OS installation, it is an excellent idea to creata bootable partition on an external hard drive, and install OS from it. Firstly, download the Microsoft Media Creation Tool and connect the external hard drive to a working computer. When being asked “what do you want to do?”, select “Create installation media (USB flash drive, DVD, or ISO file) for another PC”,  click “Next” and follow the guides to create a Windows 10 bootable partition.

Create Installation Media

After that, connect the external hard drive with the bootable partition to your computer. Turn on your computer and press a specific key to boot into BIOS and modify the boot order to make your computer boot from the external disk. Then follow the prompts to install Windows 10 from the external hard drive partition.

Windows 10 Setup

2. Bring your Windows 10 everywhere to boot other computer

If you are always on the business trip and need to bring your familiar operating system everywhere, you can create a portable bootable external hard drive. For this, you can use the “Windows To Go” function Microsoft provides. It enables the creation of a Windows To Go workspace that can be booted from a USB-connected external drive on PCs. But it is only available in Windows 10 Enterprise/Education and Windows 8/8.1 Enterprise Edition, and requires the USB drive is certified and over 32GB.

To get rid of all those limitations, you can use the AOMEI Partition Assistant Professional software instead. It comes with the “Windows To Go Creator”, which allows you to transfer Windows ISO to the external hard drive, or directly migrate the operating system to the external disk to make it bootable.

Win To Go Creator

3. Repair Windows 10 startup issue

To create a bootable external hard drive for repairing Windows startup problems, the AOMEI Partition Assistant Professional can also help you a lot. Its “Make Bootable Media” allows you to create an emergy bootable drive and boot the computer with startup issues.

Make Bootable Media

Once booting PC from the bootable disk, you will see the AOMEI software running, then you can try to repair the boot problems if they are triggered by damaged MBR.


In this post, we have shown how to partition Windows 10 external hard drive without losing data via different tools. Choose one based on your requirements. As described above, the AOMEI Partition Assistant Professional is quite versatile with many amazing functions. Besides all features listed eariler, it is also able to clone hard drive, transfer OS to SSD, align partitions, convert MBR to GPT without deleting partitions, etc. If you want to better manage the Server disk partitions, please try the AOMEI Partition Assistant Server.

Emily · Staff Editor
Emily is an English editor of AOMEI Technology; she has a great passion for providing easy solutions for people to tackle with all disk or partition management problems. In addition to writing articles about disk/partition management, she also edits great tutorials on how to back up and restore disk for data security. In her spare time, she loves to learn computer skill to improve herself or stay with her family to enjoy a good day.