How to open a .fits file
Quick, free ways to open FITS on any system.
A .fits file is a Flexible Image Transport System. If double-clicking does nothing, your computer simply does not have an app that reads FITS yet. Here is how to fix that on each operating system, using free software wherever possible.
Open a .fits file step by step
- Confirm the file really is a .fits. Drop it into the WhatFileType file identifier, which reads its signature without uploading anything.
- On Windows, open it with SAOImageDS9 or Python (astropy).
- On Mac, use SAOImageDS9 or Python (astropy).
- On Linux, try SAOImageDS9 or Python (astropy).
- Still stuck? Convert the .fits to png, which opens more widely.
Best apps to open .fits files
Windows
- SAOImageDS9
- Python (astropy)
- FITS Liberator
macOS
- SAOImageDS9
- Python (astropy)
Linux
- SAOImageDS9
- Python (astropy)
- ds9
!
Before you open it: Safe. FITS is astronomical data with a text header; it does not execute.
Frequently asked questions
Why can't I open my .fits file?
Almost always because no installed app understands FITS. Install one of the apps above, or convert the file to a format your existing software already reads.
How do I open a FITS file?
Astronomers use SAOImageDS9 to view the images, or read them in Python with the Astropy library. General image viewers usually cannot open FITS.
What is a FITS file used for?
Storing astronomical images and data tables from telescopes and space missions, along with a rich metadata header describing each observation.