FITS to WIM 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. Extracting WIM to ZIP exposes the files inside Windows images without deployment tools.
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 WIM
| FITS | WIM | |
|---|---|---|
| Compression | None (optionally Rice/GZIP) | XPRESS/LZX variants |
| Best for | Telescope frames, science data | Windows deployment media |
How to convert FITS to WIM
- 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 WIM container — no re-encoding, no quality change.
- 3
Download results
Download the finished WIM 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 WIM format
WIM (Windows Imaging Format) is how Microsoft ships Windows itself: the install media and deployment images are WIM files, holding a complete filesystem snapshot with single-instancing (identical files stored once). It is Windows' answer to tar — file-based rather than sector-based.
Opening one without deployment tooling (DISM, 7-Zip on Windows) is awkward. Extracting WIM to ZIP exposes the files inside — drivers, scripts, provisioned apps — on any system, no Windows required.
+Strengths
- ✓Windows' native image format
- ✓Single-instancing deduplicates identical files
!Limitations
- −Opaque without Microsoft tooling
- −Files inside may be Windows-locked
Why convert FITS to WIM?
Converting makes sense where the strengths of WIM meet what FITS cannot give you. Windows' native image format 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 WIM 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 WIM?
No — WIM 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.
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.