FITS to ZIP Converter
Processing entirely on your device — large files may take a moment.
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. ZIP is the safest archive to share — no special software needed on the receiving end.
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 ZIP
| FITS | ZIP | |
|---|---|---|
| Compression | None (optionally Rice/GZIP) | Deflate / store |
| Best for | Telescope frames, science data | Universal sharing |
How to convert FITS to ZIP
- 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 ZIP container — no re-encoding, no quality change.
- 3
Download results
Download the finished ZIP 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 ZIP format
ZIP (PKWARE, 1989) is the archive format the world agreed on: per-file Deflate compression (or plain store), a central directory that lets tools list and extract single files without touching the rest, and thirty-five years of universal support. Windows, macOS, Linux, phones and browsers all open ZIP natively.
Its compression ratio is middle-of-the-road next to 7z, and its encryption story is genuinely mixed: the classic ZipCrypto is broken, while AES-256 works only in tools that opted in. For maximum compatibility of everyday sharing, though, ZIP remains the only safe answer.
+Strengths
- ✓Opens natively on every platform
- ✓Random access: extract one file, skip the rest
- ✓Thirty-five years of tooling maturity
!Limitations
- −Weaker compression than 7Z/RAR
- −Classic encryption (ZipCrypto) is broken
- −No built-in recovery records
Why convert FITS to ZIP?
Converting makes sense where the strengths of ZIP meet what FITS cannot give you. Opens natively on every platform Meanwhile Not display-ready One pass through the converter above puts your file on the right side of that trade-off.
Frequently asked questions
Is this FITS to ZIP 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 ZIP?
No — ZIP 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.
Can I convert several FITS files at once?
Yes — drop as many files as you like into the tool and they are converted in one batch. When more than one file comes out, everything is bundled into a ZIP for a single download.
Will transparent areas survive the conversion to ZIP?
Transparency is kept whenever ZIP 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.