LZMA File Format (.lzma)
An LZMA file is a single stream of data compressed with the raw LZMA algorithm inside its original, minimal container, the format that came before both the 7z and xz formats now built on the same compressor.
LZMA at a glance#
| Full name | LZMA compressed archive |
|---|---|
| File extension | .lzma |
| Category | Archives |
| Developer | Igor Pavlov |
| Compression | Lossless |
| FileFlip support | FileFlip reads and writes this format |
What a .lzma file can hold#
These are the things a LZMA file either supports or does not, and they are what decides whether a conversion keeps everything or quietly drops something.
| Lossless compression | Yes |
|---|---|
| Streaming | Yes |
Strengths and limitations of LZMA#
What LZMA does well
- Decompresses with the same LZMA decoder that powers 7z and xz, so the core compression is well tested
- Simpler header than xz, just a properties byte, dictionary size and uncompressed size, which made it easy for early tools to adopt
- Still supported for reading by 7-Zip and p7zip, so .lzma files from the early 2000s still open today
Where LZMA falls short
- No integrity check built into the format, unlike xz, which is exactly the gap xz was created to close
- Largely obsolete as a distribution format; almost nothing compresses to .lzma by default anymore
- The uncompressed-size field in its header is sometimes left unknown, which can trip up decoders that expect it
An LZMA file mostly turns up when opening something old rather than something worth creating new; xz supersedes it for anything being compressed today.
Convert an LZMA file to xz when it needs an integrity check or has to be re-shared, since xz is the actively maintained format built on the same compressor.
How to open a .lzma file#
A .lzma file opens in the programs below, grouped by the platform you are on. If you would rather not install anything, FileFlip converts LZMA into a format your machine already opens, and it does it in the browser tab rather than on a server.
| Platform | Programs that open it |
|---|---|
| Windows | 7-Zip |
| macOS | Keka, p7zip |
| Linux | p7zip, xz-utils (unlzma) |
| Web | FileFlip |
LZMA questions people ask#
What's the difference between LZMA and XZ files?
An LZMA file uses the original .lzma container: just a properties byte and dictionary size in front of the compressed stream, with no integrity check. XZ wraps the same LZMA2 compression in a newer container that adds checksums and multi-stream support, which is why xz replaced .lzma as the default years ago.
Is LZMA the same compression as 7z uses?
Yes, the LZMA algorithm inside a standalone .lzma file is the same compressor 7-Zip built its 7z format around, and the two share the same decoder. The difference is the container: .lzma is a minimal raw wrapper, while .7z is a full archive format that can hold multiple compressed files with checksums and encryption.
How do I open an LZMA file?
7-Zip on Windows and its Linux and macOS port, p7zip, both extract .lzma files directly. On Linux, the xz-utils package also installs an unlzma command specifically for this legacy format.
Converting LZMA files#
Convert LZMA to another format
Convert another format to LZMA
Every conversion runs inside your browser. The file is read from your disk, the work happens on your own machine, and nothing is uploaded. How FileFlip works names the engine behind each family and how to verify that for yourself.