Complete Guide to Zip part in 5 clear Points

zip part

Zip part is a file format that indicates that a compressed zip file is currently in its part or temporary state. It could also mean that a particular compressed zip file has been divided into parts, but this case is usually uncommon. The zip part usually shows up as a zip.part extension, which stands for an incomplete zip file. The Mozilla Firefox browser uses this .part extension for files downloaded in the browser. If the download gets stopped or remains incomplete for some reason, then the zip part file can stay in the file system as a temporary file.


What are ZIP files?

Zip files can be thought of as an abstraction of a normal folder on your computer storage that can contain files or other sub-directories in itself in compressed form. These zip files can support lossless compression, which means that no data is lost while decompressing the file or data. Due to features like lossless compression, high compression rate, and ease of using the zip files are widely used on the internet to transfer extensive data or big files. Any data can be easily compressed into zip format using programs like WinRAR, WinZip, or 7Zip, etc., and the same can be used for decompression.

.part Files

The .part file extension means that the file is not completely downloaded or currently being downloaded. When they download a file, Download managers create a temporary version of the file that is variable in size. You can observe the size of the temporary file growing as the file is being downloaded. The download manager adds the .part extension to the file’s original extension to distinguish and identify the file as partially downloaded.

zip part file stored in the downloads folder
Incomplete .part files stored in the system.

Zip part file Mozilla Firefox

The Mozilla Firefox browser is the second most used internet browser after the chromium-based browsers. The browser, in particular, uses the .part extension for its downloading files. The download manager of the firefox browser adds the .part extension to the current downloading files. Therefore if you happen to download a zip file from the internet, then the download manager of the firefox browser would save it as while it is being downloaded. Once the download is finished, then the .part extension is removed. If for some reason, the downloading gets interrupted, then the zip part file can stay like that in its temporary form.

How to deal with zip part files

Suppose you were downloading something in the zip format using the firefox browser, and it got interrupted, or you happen to find some zip part files arbitrarily on your file system. In that case, you could employ some tricks to either open the file or redownload it entirely.

Redownloading the file

If your download got interrupted in the middle of a download or you have a zip part file on your system that isn’t opening, then try doing the following things to continue to download the file or redownload it entirely.

  • Open the web brower and head to the downloads sections. Check if there are any unfinished downloads in the download manager. If there is any partially downloaded file, try to contine the download process. If the download link is active and secure downloading protcol is used then chances are the downloading would continue where it left off. After the download is finished the .part would be removed from the file and it would become accessible.
  • If the redownloading doesn’t continue or the download link expired then go to the downloads folder, delete the .part file and download the file agian.

Renaming the .part file

Suppose you were downloading a file of arbitrary size x. if your download is completed, the file is still saved as a .part file. Check the properties of the file. If the file size is exactly as it should be, i.e., x units, that means the file has been downloaded entirely, but it is still saved as a temporary file. To make the file executable or readable, rename the file and remove the .part extension from its name, and it would work.

We are renaming the .part file.
We are renaming the .part file.

This trick only works for the files that have been downloaded completely. If there is any data missing in the file, it simply won’t work. Though most media files such as music or videos are downloaded sequentially can be played after renaming, only the downloaded part would be playable, not the entire content. In the case of zip part files, even if one bit of data is missing, the decompression won’t work, and the file corruption error message would be logged.

Combining zip part files using 7zip

7zip icon.
7zip icon.

Sometimes due to transfer data limitations such as maximum email size, a zip file is broken into parts or pieces to be able to attach and send through the email. The receiver receives the files in parts, and the extensions of the files are labeled z01, z02, .., and so on. The receiver, in this case, is supposed to concatenate the file in the correct order to get his original data. This can be quickly done with the help of open-source and free software such as 7zip. Follow the given steps to combine zip part files.

  • Put all the files together in one directory in sqeuential order.
  • Open the 7zip file manager.
  • Head to the directoy in which files are stored.
  • Right click on the first file.
  • Select the combine files option in the menu.

All the files would be combined into one zip file, which can now be easily extracted using 7zip. 7zip can be downloaded from

We are combining parts of the zip file using 7zip.
We are combining parts of the zip file using 7zip.

FAQs on Zip part

What other file extension indicates a temporary file?

.temp appended with the original file extension represents that the file is temporary.

What are download managers?

Download Manager is a program that is specially dedicated to managing the downloading of data in files. It is usually a part of the browser but can also be a standalone program.

What is the compression ratio?

It is the ratio of the relative reduction in the size of the data to the original size of the data.
ΔX/X. Where X is the original size and ΔX is the relative change in size.


The zip part files are not that much of a concern. The .part appended at the end of the file’s original extension only indicates the file being temporary, incomplete, or variable in size. In this article, we provided you with complete information regarding the zip part files and how to deal with them. We also showed how to combine the parts of the zip file into one file and then decompress it.

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