FITS to PGM 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. Convert PGM grayscale to PNG/JPG for viewing, or emit PGM for scientific pipelines that require raw pixel honesty.
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 to convert FITS to PGM
- 1
Select your files
Drag & drop your FITS files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to PGM". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted PGM file individually, or grab everything at once as a 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 PGM format
PGM is netpbm's grayscale format: a two-line text header, then raw 8 or 16-bit luminance samples with no compression and no metadata. That raw honesty made it the default exchange format of computer-vision research, image-processing coursework and any pipeline where "what you read is exactly the pixel value" matters.
Converting PGM to PNG or JPG just normalizes it for humans; converting back down preserves every value bit-exactly when the pipeline needs numbers, not pictures.
+Strengths
- ✓Bit-exact pixel values, no color management surprises
- ✓16-bit depth support
- ✓Trivially parseable
!Limitations
- −No compression — large files
- −Grayscale only
- −No embedded metadata
Why convert FITS to PGM?
Converting makes sense where the strengths of PGM meet what FITS cannot give you. Bit-exact pixel values, no color management surprises 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 PGM 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 PGM?
No — PGM 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.
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.