How to Delete Duplicate Files

by Contributor

If you've found multiple cases of duplicate files on your computer system, you're not alone. A variety of free programs exist for every operating system to detect and delete duplicate files from your hard drive. These programs can match files by file name, date or even checksum.

Step 1

Download and install a duplicate file finder for your OS. Although it is possible to locate duplicates manually or even to write simple scripts to do the job for you, a program with a nice GUI will take most of the hassle out of this task. Some free programs available include DoubleKiller for Windows (bigbangenterprises.de/en/doublekiller), MrClean for Mac (download.cnet.com/mac) and FSlint for Linux (pixelbeat.org/fslint).

Step 2

Launch the program you installed. When the window appears, select the directories you want to scan for duplicates. In FSlint and MrClean, the directory selection is at the top of the very first window you see. In DoubleKiller, you'll need to select the "Options" tab and choose your directories there.

Step 3

Tell the program how to detect duplicates. The default settings are usually by file size and checksum, but you can also choose names and dates. It's best to use a combination of search options. The default options of file size and checksum are typically good enough to catch most of your duplicate files.

Step 4

Click the "Find" or "Run" button in your program. Depending on the number of folders you are searching and the speed of your computer, it may take several minutes for the search to complete. When the search is finished, a list of potential duplicates will be displayed in the main window of the program.

Check the duplicates you want to delete in DoubleKiller and MrClean, and click "Delete." In FSlint, select multiple files by holding down the "Ctrl" key and clicking the file names with the mouse button. Click the "Delete" key on your keyboard to get rid of the duplicate files.


  • All three of these programs allow comparing files from locations such as CD drives, external hard drives and USB flash drives.
  • File size refers to the number of bytes in the file. This is a strong search method, as duplicate files will almost always be the same size.
  • Checksums are short strings of letters and numbers that are generated by examining the contents of a file. There is only a miniscule chance that two different files will share the same file size AND checksum.
  • Date refers to the date on which a file was created or last modified. This is usually good for catching duplicates, but it is possible that small discrepancies will appear in dates when files are copied and recopied to many different locations.
  • Names are the weakest way to detect duplicates. It is very likely that you will have two very different files on your hard drive that happen to share the same name, and it is also very likely that you have duplicate files which have been renamed over time.


  • File size will not, for example, detect two copies of the same picture when one of those pictures has been resized. And it risks picking up two unrelated files that happen to be exactly the same size.
  • It may be tempting to just scan the "C:\" drive or the root folder, but by doing so, you risk having important system files appear in your search results. Be careful about deleting duplicate files that you don't recognize.
  • Most duplicate finder programs will delete files directly rather than sending them to the recycle program. So be very cautious when you delete duplicates.

Video of the Day

Brought to you by Techwalla
Brought to you by Techwalla

More Articles