How to use the ZIP to 7Z converter
- Select one ZIP or a whole set.
- Leave Maximum compression as it is or choose another level; under More settings you can add a password for the 7Z.
- Click Convert to 7Z and save the new archives.
How much storage you can win back
Results depend on what is inside. ZIPs of text, logs, CSV files, HTML or source code frequently lose between a third and a half of their size. ZIPs of JPG scans, MP4s or other ZIPs hardly shrink because that content is already compressed. The page shows before and after sizes for each file, so you can see which were worth it.
Nested ZIPs inside a ZIP stay as single compressed files and gain little. Extract them first if you want the best ratio.
Stronger protection for sensitive records
Many ZIPs from scanners and older software still use ZipCrypto, which is vulnerable to known-plaintext attacks. Protect the 7Z with a password and it gets AES-256, with the file name list encrypted too.
The source ZIP's password goes in the first box; the password for the new 7Z is set separately under More settings.
Choosing the level for an archive clean-up
Maximum is preselected because the point of this page is saving space. Fast or Normal finish sooner when you are working through dozens of old ZIPs and only want a quick win.
Each 7Z is named after its ZIP, so 2019-invoices.zip becomes 2019-invoices.7z. Keep the originals until you have opened one of the new archives and checked it.
Questions
Who can open the resulting 7Z?
Windows 11 and Linux usually can. On macOS, iOS and Android the recipient needs a 7Z-capable app, for instance Keka, The Unarchiver or a suitable file manager.
Is anything lost in the change?
No. Contents, names, folder paths and dates carry over exactly.
Is Ultra worth it?
Only for big text-heavy archives you will keep for years. Maximum lands close to the same size in much less time.