How to find duplicate files on external hard drive

If you are looking for the best software to remove duplicate files on Mac, a free application Duplicate File Finder is exactly what you need. It allows you to identify double files on any disk or folder on your local disk, external drive or network drive.

Whether you are looking for duplicate videos, music copies in iTunes, duplicate pictures and even for similar photos, this duplicate detector will save you time, and help clear gigabytes of useless file copies.

This app is a fast duplicate file finder. However, we would like to give you some recommendations to improve your experience and help you identify duplicate files on your external drive in less than a minute.

1. How to find and remove duplicates from an external drive

After you have set up the application settings, you can start searching for duplicates. Please note that the scanning process depends on the amount of data that you have on the external drive. The more gigabytes you have, the longer the application will analyze the disk. To find and delete identical files from your external drive, follow these steps:

  1. Click on the Plus button and select an external drive. You can select the entire drive or select specific folders. Then, click on the Scan button.
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  3. After a while, you will see the scan results. Click on the interactive chart to see a specific type of duplicate files. Click the Duplicate Files button in the top menu bar to see all duplicates in detail.
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  5. Then you will see a list of groups of duplicate files that you have, and their location on the external drive. Skim the items and select the unneeded files in the group. You can also click on the Auto Select button. This option allows the application to automatically select duplicates according to your preferences. Then, click on the Review & Remove button.
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  7. Review the duplicate files you want to delete and click on the Remove button.
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  9. By default, the files are moved to the Trash. But, you can set to permanently delete files or transfer them to a special folder.

Note, when you scan an external drive, you should check some important points for the successful removal of duplicates.

  • Your external drive should have a Trash bin, which is created when you remove a file via Finder.
  • Your disk has the necessary extension (NTFS)  and is writable. You should have a driver on the disk, which allows you to manage its files.

2. How to speed up searching for duplicates on external drive

Recently, we were asked by one of our users what to do if the search for duplicates on a huge external disk takes too much time.  Let’s see why this may happen and how it can be solved.

First, we would like to mention that the scanning time depends on the speed of your disk and its connection speed. Duplicate File Finder compares the files’ content byte-to-byte to identify duplicates. A slow disk or slow connection interface may increase the search time. Nevertheless, you can scan, not necessarily the whole disk, but specified folders or you can set the minimal file size of files for the scan.

1. Skip the Time Machine backups to be scanned

If you use your External drive for making Mac backups and want to find duplicates on the drive, it’s strongly recommended that you add the Time Machine backup folder to Skip List. Time Machine tracks the changed files and makes backups on the hour. This means that when Duplicate File Finder scans your drive, it checks useless data of tons of backup copies byte-to-byte, which may take a lot of time.

To exclude backups from being scanned, go to the app’s Preferences and switch to the Skip List tab. Here you can add any folder to the Skip List. Use the “Plus” button to add any folder or your backup folders to Skip List.

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2. Skip the smallest files from the scan

If you want to find only the biggest duplicates and quickly free up some disk space, you can limit the size of files to be scanned and skip scanning the smallest files; this means the smallest files will not be checked. As a result, you will find the biggest duplicates in minutes. It makes sense to use this tip when you have a huge and slow external drive. To change the app’s settings and skip scanning the smallest files go again to Preferences → switch to the General tab → select “Skip files smaller than..” and change the reflection on the slider.

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You can set different sizes for better performance and find as many duplicates as you need.


Duplicate File Finder is a software tool, which helps to remove unwanted duplicate files from various storages. It has a user-friendly interface and simple in use. So even if you are not a tech-savvy person, you will easily find and delete unneeded duplicates from your Mac hard drive or an external drive. Free download Duplicate File Finder from the App Store to free up your disk space.

We hope these tips are useful for you. Here is also a set of articles about Duplicate File Finder software that may interest you.

If you still have questions, feel free to contact our support team. We are here to help you.