Why does the CrashPlan app show a different number of files than my computer?

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If you compare the number of files on your computer to the number of files the CrashPlan app says it's backing up, you may notice a difference. This article explains why there can be a discrepancy between your computer and the CrashPlan app.

Compare the number of files

You can see information about a folder, including the number of files it contains and its total size by right-clicking (Windows) or control-clicking (Mac) on a folder.

If you compare the number of files reported by your computer to the number of files reported by the CrashPlan app for the same folder, you may notice a difference.

The CrashPlan app reports more files than your computer

Every computer contains hidden files that don't display by default when you're browsing files (examples include ”.DS_Store” and ”desktop.ini” files). They're hidden because they aren't files you use directly, but your computer uses them to operate.

The CrashPlan app detects hidden files and backs them up, just like it backs up the files that you can see. The combined total of normal files and hidden files is the total reported on the Backup tab of the CrashPlan app. As a result, the CrashPlan app may report that it is backing up more files than your computer.

The CrashPlan app reports smaller total file size than your computer

It's also possible that the CrashPlan app reports backing up less total data than your computer says it's storing. For example, your operating system may report that a folder takes up 10 GB of space, but the CrashPlan app says it's only backing up 9 GB from that same folder. There are several reasons that this may happen:

  • De-duplication and compression: Due to de-duplication and compression that occurs during the backup process, the CrashPlan app will often show the data stored size as smaller than the selected size or the file size on your computer. 
  • Admin excludes: The CrashPlan app is designed to avoid backing up some files that your computer uses to operate. The CrashPlan app doesn't back these files up because they can't be restored with the CrashPlan app. The only way to restore those operating system or software files with functionality is to fully reinstall the software.
  • Other exclusions: You (or your organization's backup administrator) can also configure the CrashPlan app to prevent backing up some files and file types.

The CrashPlan app reports larger total file size than your computer

In some cases, the stored size is larger because your backup archive includes multiple versions of your files and includes deleted files.

Calculation differences

Even after accounting for excluded files, you might see a file size discrepancy between the total reported on the Backup tab and the total reported by your computer for the same folders.

Calculation background

In a base-10 counting system, storage is measured by multiples of 10. For example, a kilobyte is 1000 bytes, a megabyte is 1000 kilobytes, and a gigabyte is 1000 megabytes.

In a binary or base-2 counting system used by many computers, a kibibyte is 1024 bytes, a mebibyte is 1024 kibibytes, and a gibibyte is 1024 mebibytes. These totals are calculated by the exponential power of two. For example, 210 = 1024.

The practical result of this is that while base-10 and base-2 systems both measure storage, the labels and values are different. Think of it like the difference between miles and kilometers. You can say that the distance between two points is a mile, or that it's 1.6 kilometers. But no matter what measurement system you use, the physical distance is the same.

Calculation results

To keep the CrashPlan app's functions streamlined and efficient, it "speaks" to your computer using the computer's native language of base-2. But on the Backup tab, it uses base-10 to report the total to you.

If your computer uses a base-2 system and says a folder is 1 MB in size, the CrashPlan app reports it as about 96% of that amount—the difference between 1024 and 1000. If it's 1 GB, the amount reported is closer to 93%, and so on as the volume increases.

Keep in mind, however, that different operating systems use different methods of reporting storage:

  • Windows uses base-2.
  • Mac uses base-10.
  • Linux uses base-2.

Storage displayed in the CrashPlan app versus the CrashPlan console

The CrashPlan app and the CrashPlan console both display storage size as "MB" or "GB", but those acronyms mean different things:

  • In the CrashPlan app, storage is displayed in megabytes or gigabytes (base-10 system). 
  • In the CrashPlan console, storage is displayed in mebibytes or gibibytes (base-2 system). 

So, for example, while your CrashPlan app shows that the space used at a particular destination is 1.5 GB (1.5 gigabytes), your CrashPlan console will show the used storage at the exact same destination as 1.3 GB (1.3 gibibytes). It's the same amount. It's just measured in different ways.


The CrashPlan app may show different values than your computer and it's usually not a cause for concern. However, you can verify that all of your files are backed up by doing the following: 

  1. In the CrashPlan app, go to restore files
  2. Select your device’s name to navigate to your device’s root folder. This selects all of your backed up files.
  3. The CrashPlan app calculates and displays the total size. If this size is close to the selected size, all of your files are backed up.

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