Convert ZIP to 7Z
Free online converter for ZIP files. High-ratio archive from the 7-Zip project. Nothing to install, no watermark, and every file is deleted automatically.
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Upload a ZIP file to convert it to 7Z. Up to 3 files at once, 100 MB each.
Free · up to 3 files · 100 MB each · files deleted automatically after 1 hour.
About ZIP and 7Z
ZIP .zip
The archive format every operating system opens without extra software. Each file inside is compressed separately, so any one of them can be read without unpacking the rest.
Good for
- Built into Windows, macOS and Linux — nothing to install
- Random access: extract one file without expanding everything
- Supports password protection
Trade-offs
- Compresses less than 7z or tar.gz
- Per-file compression misses redundancy between files
- Its legacy encryption is weak — only AES is worth using
application/zip
7Z .7z
The high-compression archive format, using LZMA. It routinely produces the smallest file of anything here, at the cost of time and memory.
Good for
- The best compression ratios available here
- Strong AES-256 encryption
- Solid mode compresses similar files together very effectively
Trade-offs
- Needs software installed on Windows and macOS
- Slow to compress, and memory-hungry
- Less universal than ZIP for sending to other people
application/x-7z-compressed
ZIP and 7Z side by side
| ZIP | 7Z | |
|---|---|---|
| Compression | Per-file (Deflate) | Solid (LZMA) |
| Typically used for | Sending several files as one, universal exchange | Maximum compression, long-term storage |
What changes when you convert ZIP to 7Z
The archive is rebuilt, not renamed
Your ZIP is unpacked in full and its contents are written into a new 7Z. Nothing is passed through untouched, so the compression is done again from scratch at the level you choose, and the resulting size depends on that setting rather than on how the ZIP was originally made. The folder structure inside is preserved exactly.
These two store files differently
ZIP compresses each file separately with deflate, so any single file can be read without touching the rest. 7Z compresses with LZMA, usually the tightest of these formats, so supports random access, though at a higher cost to decompress. That difference is the real reason to pick one over the other: per-file compression lets a tool pull out a single entry cheaply, while compressing everything as one stream finds patterns across files and usually ends up smaller.
You choose how hard it compresses
Because the archive is built again from scratch, the compression level is yours to set rather than inherited from the ZIP. It defaults to 6 — the setting that has been the sensible middle ground for deflate for thirty years. Raising it buys a few percent for a disproportionate amount of time; lowering it is worth doing for large archives of already-compressed material such as photographs or video, where there is nothing left to squeeze.