What is 7z file?

A 7z file is an archive in the open 7z format, created by Igor Pavlov for the free 7-Zip program. It often compresses documents and software smaller than ZIP, using methods such as LZMA2.

It also supports AES-256 encryption, including encrypting file names so nobody can see what is inside without the password.

Support is growing but not universal. 7-Zip runs on Windows, recent Windows 11 versions can open 7z files, and Macs need a third-party app. For a recipient who is not technical, ZIP is simpler.

• Windows 11 (recent versions): double-click it in File Explorer, or right-click and choose Extract All.
• Older Windows: install 7-Zip, then right-click and choose 7-Zip > Extract Here.
• Mac: use a free app such as The Unarchiver or Keka.
• Phone or any computer: use an online 7z extractor, such as the one on this site.

1. Select the files, right-click and choose 7-Zip > Add to archive.
2. Set Archive format to 7z.
3. Type a long password twice. Encryption is AES-256.
4. Tick Encrypt file names so the list of files is hidden too.
5. Click OK, send the archive, and share the password another way, such as by phone.

Keep the password safe. There is no way to recover the contents without it. 7-Zip can also split an archive into parts with the Split to volumes box, which helps when one file is over a size limit; the recipient then needs every part.

• Choose 7z for large collections of documents, code or text where better compression helps, or when you want file names hidden as well as contents.
• Choose ZIP when the recipient is on a Mac, a phone or an older PC, or is not comfortable installing software.
• Either is fine for photos and videos. Neither will shrink them much.

If you send a 7z to someone who has never seen one, add a line to your message naming a free app that opens it. It saves a round of emails.