How to Extract Split 7z Files (.7z.001, .7z.002)

Why 7z Archives Get Split

7-Zip's Split to volumes option (or the -v switch on the command line) cuts the archive into fixed-size pieces. People do this to fit upload limits, email attachment caps, FAT32's 4 GB file limit, or old storage media. The pieces aren't separate archives; part 2 is just the next chunk of bytes after part 1.

That's different from RAR's multi-volume sets (.part1.rar, .part2.rar), where each volume has its own headers. For RAR, see the section on missing volumes in why a RAR file won't open.

Before You Start: Check You Have Every Part

Split archives fail if anything is missing. Check that:

• The numbering is continuous: .001, .002, .003 with no gaps.
• All parts except the last are the same size. The final part is usually smaller.
• Every part has finished downloading; no .crdownload or .part files remain.
• The base name is identical. backup.7z.001 and backup (1).7z.002 won't be recognised as a set.

Method 1: Open the .001 File in 7-Zip

On Windows with 7-Zip installed:

1. Put all the parts in one folder.
2. Right-click name.7z.001 and choose 7-Zip → Extract to "name\".
3. 7-Zip reads the following parts in order and extracts the contents.

On a Mac, Keka handles split 7z archives in the same way: open the .001 file with all parts beside it.

On Linux:

7z x backup.7z.001

Method 2: Join the Parts Into One .7z File

Joining is useful when you want a single file for an online opener, a backup or a tool that doesn't understand split volumes. It's safe because the split was a plain byte split. Make sure you have enough free disk space for a full copy.

Windows (Command Prompt)

copy /b backup.7z.001 + backup.7z.002 + backup.7z.003 backup.7z

The /b flag means binary copy; without it, Windows may treat the files as text and corrupt the result. For many parts, 7-Zip's Combine files command (right-click the .001 file in 7-Zip File Manager) does the same job without typing every name.

macOS and Linux (Terminal)

cat backup.7z.0* > backup.7z

The shell expands backup.7z.0* in alphabetical order, which matches numeric order as long as every part has the same number of digits (001 to 999). Check with ls backup.7z.0* first if you're unsure.

Check the Result

A rebuilt .7z should be exactly the sum of the part sizes. You can then test it:

7z t backup.7z

"Everything is Ok" means the archive is intact.

Method 3: Extract the Joined File Online

Once the parts are combined into one .7z file, you can open it in an online 7z extractor to browse and download its contents without installing 7-Zip, provided it's within the upload limit (1 GB on SimpleTools24). The online opener doesn't accept the separate .001 and .002 pieces, which is why joining comes first.

Which Tools Understand Split 7z Archives?

When in doubt, joining the parts first is the most compatible route: almost any 7z-capable tool can open the rebuilt file.

Not Every .001 File Is a 7z Archive

The .001 extension only means "first piece". It's also produced by HJSplit, some ZIP splitters, and disk-imaging tools. Clues to the format:

• name.7z.001 → 7-Zip split archive; joining produces a .7z.
• name.zip.001 → a split ZIP; joining usually produces a valid .zip.
• name.001 with no other extension → could be anything. Join the parts, then check the first bytes. A 7z archive begins with 37 7A BC AF 27 1C.

Troubleshooting

"Unexpected end of data" or "Missing volume"

A part is missing or incomplete. Compare sizes: every part except the last should match exactly.

"Cannot open file as archive" After Joining

The parts were joined in the wrong order, one part is damaged, or the original wasn't 7z. Rejoin carefully, or check the first bytes of the result. More causes are covered in fixing "Cannot open file as archive".

CRC Errors on Some Files

One part is corrupted. Re-download just that part; all the others can stay.

Summary

Keep every part together and open the .001 file in 7-Zip or Keka. When a tool needs a single file, join the parts with copy /b or cat, test the result, and open it normally.