7Z file format
7-Zip archive
7Z is the 7-Zip format, using LZMA/LZMA2 compression for some of the smallest archives available. It's open source but not opened natively by older systems or phones.
| Property | 7Z |
|---|---|
| File extensions | .7z |
| MIME type | application/x-7z-compressed |
| Introduced | 1999 by Igor Pavlov (7-Zip) |
| Compression method | LZMA / LZMA2 |
| Password protection | Yes (AES-256) |
| Open source format | Yes |
| Built into Windows / macOS | Windows 11 (2023+); others need an app |
| Best for | Maximum compression |
What is a 7Z file?
7z is the native format of 7-Zip, the free archiver released by Igor Pavlov in 1999. Its LZMA and LZMA2 algorithms use large dictionaries and 'solid' compression across files, often producing archives noticeably smaller than ZIP.
Strengths and weaknesses
7z offers excellent compression and strong AES-256 encryption, and it's open source. Compression is slower than ZIP, and many devices need an app to open 7z files — converting to ZIP makes them universally readable.