FITS to TAR.XZ Converter
Processing entirely on your device — large files may take a moment.
Flexible Image Transport System and XZ-compressed Tar exist for different jobs: FITS (Flexible Image Transport System) is the data format of professional astronomy — every image carries a human-readable header with telescope, exposure and world coordinates alongside the raw pixel data. Produce a TAR.XZ for the smallest possible release artifact, or to match the format a build system expects.
Because the whole conversion happens on your device, it is instant, unlimited and genuinely private — no accounts, no watermarks, no files on anyone's server. Multiple files are converted in one go.
How FITS compares to TAR.XZ
| FITS | TAR.XZ | |
|---|---|---|
| Compression | None (optionally Rice/GZIP) | XZ / LZMA2 |
| Best for | Telescope frames, science data | Source releases, Linux packages |
How to convert FITS to TAR.XZ
- 1
Select your files
Select your FITS file — it never leaves your device.
- 2
Convert instantly
The engine packs the file, byte for byte, into a TAR.XZ container — no re-encoding, no quality change.
- 3
Download results
Download the finished TAR.XZ archive.
About the FITS format
FITS (Flexible Image Transport System) has carried professional astronomy data since 1981: every file opens with a plain-text header that records telescope, instrument, exposure, filters and world coordinates, followed by raw pixel arrays — often 16-bit or float, sometimes data cubes.
Values can be negative or far above display range, so FITS never looks right in a photo viewer. Converting to PNG applies a simple scaling pass that reveals the nebula or galaxy in the numbers — good for previews, while science pipelines keep the original.
+Strengths
- ✓Self-documenting science headers
- ✓High bit depth (16/32-bit, float)
- ✓The standard of every observatory
!Limitations
- −Not display-ready
- −Files are large and uncompressed
About the TAR.XZ format
TAR.XZ pairs the tar container with XZ (LZMA2) compression — the highest-ratio member of the tar family and the de-facto release format of modern Linux distributions. The same source tree that lands 5% smaller than TAR.BZ2 and 20% smaller than TAR.GZ is why kernel.org and GNU mirrors standardised on it.
The trade is CPU time: XZ compresses slow (dictionary sizes up to 64 MB) but decompresses fast, which makes it ideal for one-time releases that get downloaded millions of times. When you need speed instead, TAR.GZ or TAR.ZSTD are the neighbouring picks.
+Strengths
- ✓Best compression ratio of the tar family
- ✓Standard release artifact of Linux distros
- ✓Fast decompression despite slow compression
!Limitations
- −Compression is CPU-heavy and single-threaded by default
- −Larger toolchain footprint than gzip on tiny systems
Why convert FITS to TAR.XZ?
There is a concrete reason this conversion exists: Not display-ready TAR.XZ sidesteps that — Best compression ratio of the tar family If that is your situation, the tool above settles it in seconds, entirely on your device.
Frequently asked questions
Is this FITS to TAR.XZ converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Will I lose quality converting FITS to TAR.XZ?
No — TAR.XZ is a lossless format, so every pixel of the converted image matches your original FITS file. You can also adjust the quality/size balance before converting when the target format supports compression.
What happens to EXIF data and other metadata?
Conversions here re-encode the image, and re-encoding generally does not carry the original metadata over. If the EXIF data of your FITS files matters (camera model, GPS, timestamps), keep the original file as the master and treat the converted copy as the shareable version.
Will transparent areas survive the conversion to TAR.XZ?
Transparency is kept whenever TAR.XZ actually supports an alpha channel. If the target format has none (like JPG), transparent areas are flattened onto a white background — that is a property of the format, not of this tool.