By Ivy / Last update October 28, 2022

Why clone hard drive to external hard drive?

Cloning hard drives is becoming more and more common for millions of Windows computer users globally. People are choosing to clone internal drives to external ones for a variety of different reasons. Below we will summarize the three main reasons why users clone their drives in Windows.

  • Clone hard drives to external hard drives for data security. Some users prefer to backup their PC to external drive in order to protect their data before something bad happens or upgrading to Windows 11 without losing data. However, the backup will need to be restored before they will be able to access the data. Cloning the drive (rather than backing it up) solves this problem.

  • Clone HDD to external SSD to upgrade the disk. Cloning the system drive to an SSD helps users who are migrating their operating system and applications to new disk. All of the contents including the partition table, the MBR (master boot record), and the registry will be cloned to the target disk and as a result the user won’t have to reinstall their system.

  • Partition layout. Transferring a hard drive to an external hard drive to have an identical partition layout.

So, what tool do you need and how to copy a hard drive to an external hard drive? Please keep on reading.

The best way to clone a hard drive to all kinds of external drives

Windows doesn’t include a built-in cloning feature in its range of backup tools, therefore, we must turn to third-party cloning software. AOMEI Backupper Standard Edition is a specialist disk cloning program that allows users to clone hard drives in Windows 10/8/7/XP/Vista and the latest system Windows 11 to external ones (such as HDDs, SSDs, and USB flash drives) in a few simple clicks. 

AOMEI Backupper enables users to clone smaller hard drive to larger drive to get more free space. You can even clone from larger hard drives to smaller ones using the Intelligent Clone function as long as the smaller drives are big enough for the cloned data.
✧ It offers the Sector by Sector Clone function to help you make an exact copy of the source disk. Even blank or logically bad sectors will be cloned.
✧ It provides you with the "SSD Alignment" option to optimize your SSD during the cloning process, especially useful when you clone your HDD to an external SSD drive.
✧ It is compatible with all Windows PC operating systems, 32 bit or 64 bit.

AOMEI Backupper is free to download, and importantly it doesn’t include ads. Why not download it to have a try right now?

Download Free TrialWin 11/10/8.1/8/7/XP
Secure Download

Step by step guide: clone HDD to external drive in simple steps

In this part, I will show you how to clone HDD to USB external drive as an example to teach you how to use this cloning software. To clone hard drive to USB external drive on a laptop, please connect the external drive to your computer using a USB to SATA adapter. If you have a desktop PC, you can directly install the external drive into one of the hard disk bays.

Note: Please note that cloning will overwrite data and files on the target external drives, so you should backup files that are important.

Step 1. Launch hard drive cloning software AOMEI Backupper, then you will see its deep-blue screen. Click Clone and then select Disk Clone to clone Windows hard drive to external.

Disk Clone

Notes: The Clone feature in the trial version can only be demonstarted, to clone hard drive to external hard drive, you need to upgrade pro trial to full version of AOMEI Backupper. 

Step 2. Select the original HDD on your computer as the source disk. Then, click Next.

Select Disk

Step 3. Select the USB external drive as the destination disk (the destination disk can also be an SSD, a flash drive, etc.). Then, click Next.

Choose Destination Disk

Step 4. Check the operation summary and click Start Clone to clone computer to external hard drive.

Start Clone

Step 5. Wait until the process reaches 100% and click Finish. Then, replace your old hard drive and boot computer from the cloned external drive to make sure it's bootable. If you keep both disks connected, please change the boot sequence in the BIOS to make the external drive the first boot option.

Helpful Tips:

  • If you want to clone every sector on the hard drive, check the Sector by sector clone box. Make sure that the target disk is larger than or equal to the source disk, or the Start Clone button will grey out.

  • If you want to migrate operating system to SSD, then you should check the SSD Alignment box to improve your SSD’s performance.

  • To resize the partitions on the destination disk, you can click Edit Partitions and choose "Add unused space to all partitions" or "Manually adjust partition size". Please upgrade to the full version of AOMEI Backupper Professional edition to use these features.

Copy Without Resizing

Please be aware that the length of time the cloning process takes varies from drive to drive. If you have a large drive with lots of data, the process may take relatively longer time. 


AOMEI Backupper Standard Edition helps you clone HDD/SSD to external drive with just a few simple clicks, so you can get a working computer back easily and quickly in the event of a disaster. And this software also applies to clone external hard drive to internal, migrate Windows 10 to M.2 SSD, clone SSD to larger SSD, and move hard drive to new computer in Windows 11, etc.

And it is crammed full of useful features and functions for managing your system. It enables you to backup your system to an external hard drive or NAS device, backup important files to cloud storage, and more! Why wait? Try it now!