Convert to FITS online

Free online converter for converting files to FITS.

How to convert files to FITS?

1
Upload your file
Click the 'Choose File' button or drag and drop your file into the upload area. Supported formats include PNG, JPG, WEBP and more.
2
Select the output format
Make sure FITS is selected as the conversion format. Adjust additional settings if needed.
3
Start the conversion process
Click the 'Convert' button and wait a few seconds. All conversions are performed on our servers.
4
Download the result
Once the process is complete, click the 'Download' button and save the file in FITS format.

Why choose our FITS converter?

We ensure quality, convenience, and support for all formats.

High-quality to FITS conversion
We guarantee precise to FITS file conversion without any loss of quality.
Support for multiple formats
You can convert your to FITS files from over 200 different formats, including images, documents, and more.
Compatible with all devices
Convert to FITS files from any device – whether it's a computer, tablet, or smartphone.
User-friendly interface
Our service is designed to make to FITS conversion easy for everyone in just a few simple steps.
Full data security
All files are transmitted and stored using advanced encryption technologies.
High-speed processing
Thanks to cloud technology, we ensure fast processing even for large to FITS files.

Convert to FITS: supported formats

Convert FITS to other formats

.FITS

FITS
Flexible Image Transport System
Data typeImage
MIME typeimage/fits
DeveloperIAU FITS Working Group (international standard; widely supported by NASA/GSFC FITS community resources)
Primary use casesAstronomical images, spectra, time series, 3D/4D data cubes (with time/wavelength axes), catalogs and calibration tables, long-term scientific archiving

What is the FITS file format?

FITS is an open standard file format for astronomical images and scientific data arrays with rich metadata headers.

FITS file characteristics

Data typeImage
MIME typeimage/fits
CompressionOptional; commonly uncompressed, or compressed via established FITS conventions (e.g., tiled image compression)
Color depthBITPIX valid values: 8/16/32/64-bit integers and -32/-64 IEEE floating point
Color spaceNot defined by the format; typically grayscale scientific values (intensity), with color rendering handled by the viewer
MetadataRich keyword/value headers (mandatory + optional + convention keywords). Headers are self-describing and store observation, instrument, WCS/time, and processing metadata
Standard / SpecificationThe FITS Standard, Version 4.0 (IAU FITS Working Group; approved 22 July 2016; language-edited 13 August 2018)
Typical file sizeHighly variable: from small headers to many GB for large mosaics and multi-dimensional cubes; size depends on dimensions, BITPIX, and compression
Year introduced1981

Advantages

The FITS file format offers several advantages that make it suitable for common use cases.

  • Industry-standard in astronomy;
  • Self-describing headers with extensive metadata;
  • Supports multidimensional arrays and tables;
  • Strong backward compatibility (“once FITS, always FITS”);
  • Broad tooling ecosystem;
  • Works well for archival and interchange

Limitations

The FITS file format has certain limitations that may affect its use in specific scenarios.

  • Common on-disk extensions vary (.fits, .fit, .fts, etc.);
  • Complex products often require FITS-aware software;
  • Some features (e.g., compression) rely on conventions and may not be supported equally by all tools;
  • No built-in encryption/authentication

Compatibility

FITS images are widely supported and can be viewed on most devices and platforms.

  • Supported platforms: Windows, macOS, Linux
  • Supported devices: Observatory and lab workstations, scientific pipelines, data archives
  • Browser support: No
  • Mobile support: No
  • Backward compatibility: Yes

Security considerations

Treat FITS as untrusted input. Standard keywords are not inherently risky, but locally-defined conventions/keywords may trigger actions (e.g., reading other files/URIs or interacting with instruments). Large files may also stress resources

License

Open standard

FITS (Flexible Image Transport System) is the de facto standard in astronomy for storing and exchanging images, spectra, data cubes, and tables. A FITS file is built from one or more header/data units (HDUs): an ASCII keyword header (fixed-length 80-character records) followed by binary data blocks. FITS supports integer and floating-point pixel arrays, multiple extensions (IMAGE/TABLE/BINTABLE), and widely used compression conventions such as tiled image compression (often stored as .fits.fz).