.7Z.001 File Extension

A 7Z.001 file is the first part of a multi-volume .7Z archive. It is typically matched with other 7Z.### files, such as a .7Z.002 file, 7Z.003 file, and so on. 7-Zip creates a 7Z.001 file when you choose to split an archive into multiple volumes, using the Split to volumes, bytes: feature.

7-Zip is a free archiving utility available for Windows. Typically, when you archive one or more files using 7-Zip, the program packages those files in a single 7Z archive. However, you can instead choose to package files in a multi-volume, or split, archive. Splitting files into a multi-volume archive can make them easier to store, upload, and download, since each volume's file size is smaller than a single-volume archive's would be. (For example, you can split what would be a single 80 MB 7Z file into eight 10 MB 7Z.### files.)

7-Zip saves multi-volume archives as a series of 7Z.### files. The first file in this series always uses the .7z.001 extension. The number of additional files included in a multi-volume archive varies, depending on the size of the files being archived and the volume size you've selected using the Split to volumes, bytes: feature.

You can use 7-Zip (Windows), The Unarchiver (Mac), or B1 Free Archiver (multiplatform) to extract the files a 7Z.001 files contains. To do so:

1. Make sure all the files included in your multi-volume archive (FileName.7z.001, FileName.7z.002, FileName.7z.003, and so on) are stored in the same directory.
2. Select your 7Z.001 file, and use your archive utility to extract its files. For example, if you are using B1 Free Archiver to extract files, navigate to your 7Z.001 file, right-click the file, and select Extract to → Extract here.

The files your multi-volume archive contains will then appear in the folder containing your 7Z.001 file.