By Delia / Last update June 23, 2021

Why can't I copy large files to external hard drive?

For security or portability reason, you may want to store important data on a removable device, but end up finding the file too large to copy to external hard drive or USB, even when there's sufficient space in it. Why did this happen, and how to transfer large files to external hard drive successfully?

Well, one possible reason is that the file is really larger than the available space of the external hard drive. But the most likely situation is as in this case - the file is too large for the destination file system.

Bought a 250 GB USB WD external drive to back up my video footage. Some files are around 7 GB. When I try to copy one file to the external hard drive, I get the message: ‘The file is too large for the destination file system’. Anyone knows what does that mean and why I can’t copy a 7 GB file to a 250 GB hard drive?

It happens because each file system has its own size limitation. FAT (also known as FAT16) only supports a file up to 2 GB, FAT32 supports up to 4 GB, as for NTFS, the maximum file size is 16 TB. You can’t transfer a file that exceeds the limit of the destination drive even when it has plenty of spare space.

Such being the case, you can take following measures to fix the problem and copy large files smoothly.

File Too Large

How to fix the problem that a file too large for external hard drive?

If you fail to copy large files to external hard drive or USB, you should check the available space and file system of the destination drive at first, and then pick a solution according to your case.

Method 1. Check your external hard drive or USB

Anyway, first check that your device is connected properly and make sure it really has more available space than the file you want to copy. If not, you can take the most direct way – prepare another external hard drive or USB flash drive with suffecient space. If you don’t have any large device, please refer to Method 4.

Method 2. Convert the file system to NTFS

If you receive the file too large for the destination file system message while the external hard drive has sufficient space, the first possibility is your destination drive has been formatted to FAT/FAT32, which has a maximum size limit of 2 GB/4 GB. Thus you can’t transfer large files beyond the amount unless you convert the file system to NTFS.

To check the file system information, first open the File Explorer > right-click the external hard drive > choose Properties > find File system under General tab.

★ Convert file system without losing data:

If you’ve stored some files in the external hard drive, this may be the best way to convert file system without data loss.

1. Press Windows logo key + R at the same time. Type cmd in the box and click OK.

2. Type the command: convert n: /fs:ntfs (“n” refers to the drive letter of external hard drive).

3. Press Enter key to run it, and enter the volume label (name) if required. Within a few minutes, FAT32 formatted external hard drive will be converted to NTFS successfully. Then you can copy large files to it as normal.

Note: There are chances that you fail to convert file system to NTFS due to low disk space, non-standard cluster, non-continuous volume, etc. If so, you can go to Method 4.

Convert File System Cmd

★ Re-format the drive directly:

This solution can help you convert FAT/FAT32 to NTFS or vice versa, but it will erase all data on the drive. Therefore, you’d better backup external hard drive before formatting.

1. Open File Explorer, right-click the drive and choose Format...

2. Find File system select box in the popping out windows, choose the option you want from the drop-down menu. Here choose NTFS.

3. Click Start and then OK to confirm the operation. Wait for a while, this external hard drive will be converted to NTFS successfully.

Tips: Alternatively, you can right-click the drive in Disk Management and Format it in similar way.

Format Usb

Method 3. Re-connect the external hard drive or USB

If you find the file too large for destination file system when the drive is already NTFS formatted, it’s probably because it's still identified as FAT/FAT32. Then you can try re-connecting the drive without physically unplugging it. 

1. Right-click Start button and choose Device Manager, or directly search for it.

2. Find the external hard drive or USB drive in the list, right-click it and choose Disable.

3. Wait for a while and then Enable it.

Alternatively, you can open Disk Management, right-click the drive and choose Eject. And to re-connect it, you need to change its status to Online

Method 4. Backup a large file into multiple smaller images

If all the solutions fail and you don’t have another usable device as destination, how to copy large files to external hard drive? Well, maybe you should give up copying and pasting manually, because a backup image takes up less space than an exact copy.

With practical software like AOMEI Backupper Standard, you can backup large files to external hard drive with preferred compression level, or even split large image into multiple smaller files. Thus the file too large for destination file system error could be readily solved without conversion. Even if the external hard drive has insufficient space, you can store these image files in multiple devices.

What’s more, as a complete Windows backup program, AOMEI Backupper provides file/folder/partition/system/disk level backup along with pratical backup options – schedule backup, intelligent sector backup, exact backup, etc.

If you have the need to schedule backup large files to external hard drive, then the incremental backup could help you back up only changed files each time to save space. You can even set up a Scheme (supported by advanced editions) to auto delete backups older than x days. Download it to have a try:

Download Freeware Win 10/8.1/8/7/XP
Secure Download

You can effortlessly use the software for daily data protection, and once there’s an image file too large to transfer to USB or external hard drive, you can split it into smaller size. Here’s an example:

How to copy large files to FAT32 external hard drive without converting to NTFS?

Preparations: Install the software on your computer and connect the external hard drive properly.

1. Open AOMEI Backupper, go to Backup tab and choose File Backup.

File Backup

2. Click Add Folder or Add File to locate the folders or files you want to backup to external hard drive.

Add Folders Files

3. Select the connected external hard drive as the destination.

Select Destination

4. Click Options > Advanced > Splitting to specify the size you want to split the image file into. Click OK to confirm it.

◆ You can select Automatic or Choose a predetermined size to fit in different devices. If you upgrade to Professional edition, you can also Custom size as you like. But please note the minimum image file size is 50MB.
◆ If you want to further shrink the image file, you can go to Compression section (above Splitting) and select a higher compression level. The higher the level, the smaller the image, and the longer it will take.



5. Click Start Backup and wait for it to finish.

Start Backup


  • After splitting, it’s recommended to keep these image files in the same directory to ensure the convenience of data management.

  • Schedule: If you want to keep the backup in external hard drive up-to-date, you can add a schedule to run the task automatically, but the destination drive should always be connected in this case. As for schedule options, you have Daily, Weekly, Monthly, Event triggers and USB plug in. The last 2 are available in advanced editions.

  • Scheme: Create backup scheme in advanced editions can delete the older backups automatically to save your storage space.



Don't panic when your file is too large to copy to external hard drive. Take some time to try above methods, or use AOMEI Backupper Standard to backup the large file into multiple smaller images. Considering external hard drives could be damaged or lost easily, you can use this freeware to backup files to cloud drives, network or NAS devices as well.

In addition, if you want to copy a partition or a disk for hard drive replacement, the Clone feature also comes in handy. With the intelligent clone technology, you can even clone a larger drive to a smaller SSD.