LZMA file format: what it is and how to use it

LZMA is the compression algorithm inside 7z and xz: raw streams squeezed harder than gzip ever managed. Learn when to use it and what to choose instead.

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What is a LZMA file?

A .lzma file is a raw stream compressed with LZMA, the Lempel-Ziv-Markov-chain algorithm Igor Pavlov built for 7-Zip: dictionary matching plus range coding that beats gzip's ratio by a wide margin at the price of speed and memory. The bare format you meet alone is rare, since LZMA normally arrives inside containers: .7z, .xz, RPM/DEB payloads and embedded firmware blobs.

When should you use .lzma?

  • Inside its containers: you are usually handling xz or 7z files, not bare streams.
  • Embedded systems: firmware and boot images still ship raw LZMA.
  • Maximum ratio for single streams: where decode time does not matter.

When is another format a better fit?

For the same algorithm with proper headers use .xz, since bare .lzma lacks integrity checks. For modern work zstd is faster at similar ratios; for compatibility gzip still reads everywhere. Bare .lzma is a building block more than a user format.

The short version: LZMA is the engine, not the car. You meet it inside 7z and xz; prefer those (or zstd) for real files.

How to open a LZMA file

On Windows

Double-click the file, or open it with 7-Zip.

On macOS

PeaZip opens LZMA files on macOS.

In your browser

Open LZMA files right in a browser tab or with the dexrr viewer. No install, no upload.

Also opens in

  • 7-Zip
  • xz utils
  • PeaZip

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LZMA technical details

Full name
LZMA compressed file
Extensions
.lzma
MIME type
application/x-lzma
Compression
Lossless
Developer
Igor Pavlov (LZMA SDK)
Specification
www.7-zip.org

LZMA questions, answered

How do I open a .lzma file?

7-Zip, xz --format=lzma, and most Unix archive tools decompress it. dexrr extracts .lzma files directly in your browser.

Can I convert LZMA files online?

Yes, dexrr decompresses .lzma locally in your browser and can repack the contents to zst, gz or zip.

Is LZMA better than GZIP?

On ratio, clearly: 20–30% smaller is typical. On speed and memory, gzip wins. For the best of both today, zstd beats each.

What is the difference between .lzma and .xz?

Same algorithm family. .xz is a container format around LZMA2 with integrity checks and metadata; .lzma is the raw codec stream.

Is the LZMA format outdated?

As a bare file, mostly. It lives on inside .xz, .7z and firmware images, which is where it belongs.