FITS to WebP Converter
Processing entirely on your device — large files may take a moment.
WebP is the go-to format for fast websites: smaller files mean quicker pages, lower bandwidth and better SEO scores. If your files are still in FITS format, this page is the shortcut: 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.
This converter runs entirely in your browser using WebAssembly — your files never leave your device, nothing is uploaded, and there are no watermarks, sign-ups or queues. Drop in several files at once to convert them as a batch.
How FITS compares to WebP
| FITS | WebP | |
|---|---|---|
| Compression | None (optionally Rice/GZIP) | Lossy and lossless modes |
| Transparency | Not supported | Supported (alpha) |
| Animation | Not supported | Supported |
| Metadata | Rich text header (WCS) | EXIF, ICC embeddable |
| Best for | Telescope frames, science data | Web images and bandwidth savings |
How to convert FITS to WebP
- 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 WebP". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted WebP 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 WebP format
WebP is Google's image format, released in 2010 and built on the VP8 video codec. In lossy mode it typically produces files 25–35% smaller than JPG at the same visual quality, and it also has a true lossless mode that beats PNG. Crucially, one format covers what used to require two: lossy photos with transparency, and even animation, all in a single container.
Browser support is no longer the barrier it once was: Safari added WebP in iOS 14 (2020), and every modern browser now decodes it. The remaining friction is with older desktop software and a hard dimension limit of 16383×16383 pixels, which rules out very large panoramas and print masters.
+Strengths
- ✓25–35% smaller than JPG at equal visual quality
- ✓Transparency and animation built into the same format
- ✓Supported by every current browser and most CDNs
- ✓Has a genuine lossless mode that out-compresses PNG
!Limitations
- −Hard limit of 16383×16383 pixels per image
- −Older photo apps and OS image viewers may not open it
- −Encoding is more CPU-intensive than JPG
Why convert FITS to WebP?
Converting makes sense where the strengths of WebP meet what FITS cannot give you. 25–35% smaller than JPG at equal visual quality 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 WebP 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 converting FITS to WebP reduce quality?
WebP uses lossy compression, so a small amount of recompression is unavoidable. The quality slider lets you choose between maximum fidelity and smallest file size — the default is visually indistinguishable for photos.
Will transparent areas survive the conversion to WebP?
Transparency is kept whenever WebP 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.
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.