What is a .7z file?
7-Zip Archive · Archive · Igor Pavlov (7-Zip) · 1999
7Z is the archive format of the free 7-Zip tool, offering some of the best compression around. It squeezes files smaller than ZIP or RAR and supports strong encryption, which makes it popular for large downloads and backups.
What is a .7z file used for?
7Z uses the LZMA family of compression to pack files noticeably smaller than ZIP, especially for large or repetitive data.
It is completely free and open, supports AES-256 encryption, and can split archives across volumes.
The catch is that older Windows and macOS do not open 7Z out of the box, so the recipient may need 7-Zip or a similar tool.
That is easing: recent Windows 11 builds can now extract 7z, RAR and TAR natively, and on a Mac the free Keka or The Unarchiver opens a 7z in one click. Large 7z archives are sometimes split into numbered parts (.7z.001, .7z.002), which the same tools rejoin automatically once every part is present.
How to open a .7z file
The .7z format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list. For a step-by-step walkthrough, see how to open a .7z file.
Windows
- 7-Zip
- PeaZip
- WinRAR
macOS
- Keka
- The Unarchiver
Linux
- p7zip
- Archive Manager
Web
- Not natively; extract locally
How to convert a .7z file
You can convert a .7z file to ZIP, TAR using a conversion tool or the export menu of an app that opens it.
.7z file signature (magic bytes)
Programs recognise a .7z file by the bytes at the start of the file, not by its name. These are the signatures for 7Z. For a full breakdown, see the 7Z file signature page.
| Hex signature | Offset | Note |
|---|---|---|
| 37 7A BC AF 27 1C | 0 | '7z' signature |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .7z file?
7Z is the archive format of the free 7-Zip tool, offering some of the best compression around. It squeezes files smaller than ZIP or RAR and supports strong encryption, which makes it popular for large downloads and backups.
Is 7z better than ZIP?
7z usually compresses smaller and supports stronger encryption, but ZIP opens everywhere without extra software. Use 7z for size, ZIP for compatibility.
How do I open a 7z file on a Mac?
Install the free Keka or The Unarchiver, then double-click the .7z to extract it. macOS cannot open 7z on its own, but either tool handles it without needing 7-Zip.
Comparisons
Related formats
Sources
Details on this page were checked against authoritative references: