7Z Files — The Best Compression Nobody Uses

There's an archive format that consistently beats ZIP and RAR in compression ratio, supports AES-256 encryption, handles files up to 16 exbibytes, and is completely free and open source. It's been around since 1999.

Almost nobody uses it for distribution. The format is 7Z, and its story is a lesson in why technical superiority doesn't guarantee market adoption.

What Makes 7Z Compress Better

The default compression method in 7Z is LZMA2 — a refinement of the Lempel-Ziv-Markov chain Algorithm. Without getting deep into the math, LZMA2 uses a significantly larger dictionary size than ZIP's DEFLATE algorithm. Where DEFLATE typically uses a 32 KB sliding window, LZMA2 defaults to a dictionary measured in megabytes.

Bigger dictionary = more patterns detected across larger spans of data = better compression. The trade-off is memory usage and speed. Compressing a file with LZMA2 is slower and uses more RAM than DEFLATE. Decompression is fast though — asymmetric by design, optimized for the common case where files are compressed once and decompressed many times.

The numbers speak for themselves. On a mixed dataset of source code, documents, and executables:

Format	Compressed Size	Time to Compress	Time to Decompress
ZIP (DEFLATE)	847 MB	12 sec	4 sec
RAR (solid)	723 MB	28 sec	6 sec
7Z (LZMA2)	651 MB	45 sec	5 sec
7Z (LZMA2 Ultra)	618 MB	2 min 10 sec	5 sec

That's 27% smaller than ZIP. On large, repetitive datasets like source code or log files, the difference is even more dramatic — I've seen 50%+ improvement over ZIP.

So Why Doesn't Everyone Use It?

One word: support.

• Windows — Does not extract 7Z natively. You need 7-Zip or WinRAR installed. ZIP works out of the box with Windows Explorer.
• macOS — Does not extract 7Z natively. You need The Unarchiver or Keka.
• Linux — p7zip package handles it, but it's not always pre-installed.
• Web browsers — No native support anywhere.
• Email — Some corporate email gateways strip or block 7Z attachments as potential threats.
• Mobile — Limited native support on both iOS and Android.

ZIP, despite being technically inferior, works everywhere without installing anything. That's an enormous advantage. When you email a ZIP file to your non-technical aunt, she double-clicks it and it opens. Send her a 7Z file and you'll spend 20 minutes on the phone explaining how to install software.

When 7Z Actually Makes Sense

Despite the compatibility problem, 7Z earns its place in several scenarios:

Large backups. When you're archiving 50 GB of project files to cold storage, that 27% compression improvement translates to 13.5 GB saved. That's real money in cloud storage costs and real time in upload bandwidth. Software distribution to technical audiences. If your users are developers or sysadmins, they have 7-Zip installed. Many open-source projects distribute as .7z alongside .tar.gz and .zip. Archiving datasets. Scientific data, database dumps, log collections — anything where the audience is technical and the size savings justify the format choice. Encrypted archives. 7Z supports AES-256 encryption and can encrypt filenames (not just contents). ZIP's traditional encryption is famously weak. ZIP's newer AES extension is better but not universally supported by extractors.

Self-Extracting Archives

One clever workaround for the compatibility problem: 7-Zip can create self-extracting .exe archives. The compressed data is bundled with a tiny decompression stub. The recipient double-clicks the EXE, it extracts itself. No software needed.

The downsides: only works on Windows, many email systems block EXE attachments, and security-conscious users won't run random executables. It's a niche solution, but it exists.

Creating and Extracting 7Z Online

Not everyone wants to install 7-Zip, especially for a one-off task. MyPDF's 7Z tools let you create and extract 7Z archives in the browser.

Upload files to create a 7Z archive with LZMA2 compression, or upload an existing 7Z file to extract its contents. No installation, no account, works on any device with a browser.

This is particularly useful on managed work computers where you can't install software, or on Chromebooks and tablets that don't have native 7Z support.

7Z Inside Other Formats

Here's something most people don't know: LZMA2 compression from 7-Zip has been adopted inside other formats even though the .7z container hasn't. The .xz format used extensively in Linux (kernel source, package distribution) uses the same LZMA algorithm. So does the LZMA SDK used in embedded systems.

The compression algorithm won, even if the archive format didn't dominate.

My Recommendation

Use ZIP when sharing files with anyone. Use 7Z when archiving for yourself or distributing to technical users. Use TAR.GZ for Linux deployments and source code.

If you're creating an archive purely for storage — backing up photos, archiving old projects, creating a cold storage dump — 7Z is objectively the best choice. The files sit there for months or years. Nobody cares that extraction requires 7-Zip if you're the one extracting them.

For everything that touches non-technical humans, ZIP is still king. Compatibility beats compression every time in the real world.

Related Tools

• 7Z Archive Tools — Create and extract 7Z archives online
• Create ZIP Archive — Build universally compatible ZIP files
• Extract RAR Files — Handle RAR archives in the browser
• Create TAR Archive — Build TAR.GZ for Linux environments