By Ivy / Last update October 31, 2022

Can I clone a hard drive with Windows 10 on it?

"I have a computer with Windows 10 preinstalled. But the hard drive for my computer run out of space and I want to clone Windows 10 (including OS, installed app, drivers, etc.) to external hard drive. Can I clone entire Windows 10 to an external hard drive and boot from the cloned drive?  Any kindly advice will be appreciated."

Clone Windows to External Hard Drive

No matter what your purpose is, you can clone Windows 11/10/8/7 to external hard drive effortlessly with the best disk cloning software. 

Why do you clone Windows to external hard drive?

For cloning hard drive in Windows 11, 10, 8, 7, the most common reason is to replace or upgrade old disk. Just imagine, after a long time use, your disk is old and fragile, maybe does not have sufficient space, thereby making your computer run slowly. Or your hard drive stops responding from time to time.

At this time, you may be annoyed and frustrated and want to get rid of this situation soon. The best way is to make a copy of everything on the original disk by cloning disk to larger disk. If you have higher requirements for computer performance, cloning hard drive to SSD will be a better choice, a little smaller is OK. It's said, an SSD is 10 times faster than the common HDD.

Also, you may want to clone Windows to external drive and use it as a backup copy. Thus, when your computer crashes all of a sudden, you can boot from the cloned drive and access your data easily and quickly.

Besides, cloning Windows saves you much energy compared with installing Windows from scratch. If you clean install Windows on an external hard drive, you only get a fresh copy of system, and you have to redo customized settings, reinstall commonly used programs and copy over your personal data. What a tough work it is!

What is the best software to clone a hard drive?

Speaking of the best disk cloning software, the most important thing is it can successfully clone hard drive to another one. This means it will clone everything on the original disk to another one and you can boot from it after cloning. 

AOMEI Backupper Professional is worth trying if you want to copy Windows to external hard drive. And it still has the following advantages.

Support cloning all brands of HDDs/SSDs or MBR/GPT disk, such as, Samsung, WD, Seagate, etc. 
Intelligent Clone: This feature ensures you can easily clone hard drive with different size, even to a smaller one. Because it only clones used sectors to another drive.
Edit Partitions: It allows you to clone and resize hard drive without leaving unallocated space. Also, it supports converting the destination disk from MBR to GPT or from GPT to MBR.
SSD Alignment: This feature is designed for SSDs to get higher performance, such as faster reading and writing speed, longer service life.
Compatible with all Windows PC systems, including Windows 11, 10, 8.1, 8, 7, XP and Vista.

Example: how to clone Windows 10 to external hard drive

By default, this software uses the Intelligent Clone feature to clone a hard drive. It will be OK if the target disk is smaller. But you need to be sure the used disk space of the original disk is smaller than or equal to the external hard drive. If not, the cloning process will also fail, please free up your disk space first. 

Then, download this software and install it on your computer. For server users, try AOMEI Backupper Server

Download Demo Win 11/10/8.1/8/7/XP
Secure Download

Learn how to copy Windows 10 to external hard drive as follows:

Step 1. Connect the external hard drive for cloning. If it's a laptop, you may need a USB-to-SATA cable.

Step 2. Open this utility, and select “Clone” and “Disk Clone” in the main page.

To clone only OS, please click “System Clone” instead.

Choose Disk Clone

Step 3. Select the internal hard drive of Windows 10 and click “Next”.

Select Mbr Disk

Step 4. Select the external hard drive you prepare and click “Next”.

Select Gpt Disk

Click “OK” to continue this operation if you have already created a backup for your important data. If not, click "Cancel" and backup files to external hard drive first.

Backup First

Step 5. Tick "SSD Alignment" if the external hard drive is an SSD.  Then, click “Start Clone” to clone computer to external hard drive.

Preview Clone

Also, you can use Sector by sector clone to keep the old partition layout or Edit Partitions to adjust the partition size on the destination disk or convert its disk type. And the latter one is more practical since it resolves two potential issues during the cloning process. 

#1: The cloned drive not show full capacity.

By default, all the cloning software makes an exact copy of source disk unless you change the partition size while cloning. To prevent this from the beginning, try the following 3 options after upgrading pro trial version. 

👉 Copy without resizing partitions: It will not resize the partition size.

👉 Add unused space to all partitions: It will reallocate the unallocated space to each partition of the target disk, appropriate for the disk size.

👉 Manually adjust partition size: It allows you to extend unallocated space to any partition on the destination disk you want. 

Edit Partitions

#2: The cloned drive not bootable after cloning.

One of the biggest reason is the destination and source disk has different partition style and you don't convert them to the same before cloning. In this situation, you can simply check Convert the destination disk from MBR to GPT or vice versa, depending on their disk partition styles. 

Both MBR and GPT are two different disk types for data storage. And you can check its disk properties in Disk Management. The overall steps are below:

  • Press Win + R to open the Run window. Then, type diskmgmt.msc and hit OK to open disk management.
  • Then, right-click the disk you want to clone and select Properties in the pop-up window.
  • In the Properties window, select the Volume tab and confirm the partition style. It can be MBR (Master Boot Record) or GPT (GUID Partition Table).

Disk Partition Style

  • Similarly, check the disk partition tyle of the destination disk. If it is still MBR, you don't need to convert the disk type. If not, please tick the Convert the destination disk from MBR to GPT option, and it may be different, depending on their disk types.
Don't use external SSD or hard drive as a boot drive, because the USB-to-SATA adapter does not provide enough power supply required for boot. Learn how to boot from the cloned external drive successfully from the next part.
If you want to clone hard drive without booting into Windows, you can choose to create a bootable USB and boot from it before cloning.
For Server users, from Server 2003 to Server 2022, please use AOMEI Backupper Server.

How to boot from cloned external hard drive

After cloning Windows to external hard drive, the process is half done. All you need to do is to replace the old disk and see if your computer can boot from the cloned drive. To boot from the external HDD or SSD, follow the steps below.

Step 1. Open the drive bay. Shutdown your computer, plug out all power, remove the hard drive bay cover with a screwdriver.

Step 2. Take out the original hard drive. Unscrew the screws holding the hard drive, then take out the existing hard drive at an angle(eg: 30 or 45 degrees).

Take Out Original Hard Drive

Step 3. Installed the external hard drive back into your computer.

Step 4. Change boot order after replacing hard drive and boot from it. 

Turn on your computer, hit the specific key in the initial screen (usually F2 or ESC) to access BIOS, go to the boot tab and use “+” to move the external drive to the first option, then press “F10” to save the change and boot from the cloned drive.


Written in the end

With the help of best disk cloning software - AOMEI Backupper Professional,  you can easily clone Windows 11/10/8/7 to external hard drive, whether larger or smaller. And it breaks the limitation of cloning MBR to GPT disk without losing data and vice versa. In addition, it can fix unallocated space left after cloning and further improve the performance of SSD disk.

Besides, this utility still provides users with many useful features. Thus, you can use it to create system backup, incremental backup, dissimilar hardware restore, create bootable USB, mirror folder to network drive, etc. Why not give it a try right now?