FITS file: How to open? The best software for opening fits files

FITS

Flexible Image Transport System

File type: Graphics file

A fits file extension is associated with the Flexible Image Transport System a standard format for astronomy images. Ae fits file stores picture image.

What is fits file?

File type category:
Graphics file

Date updated: June 23, 2025

The fits file extension is used for Flexible Image Transport System format, a most commonly used standard format for images used in astronomy. Historically, magnetic tape was the original storage medium for FITS formats.

FITS is a digital file format used to store, transmit, and manipulate scientific and other images, specially in Astronomy. A major feature of the FITS format is that image metadata is stored in a human-readable ASCII header, so that an interested user can examine the headers to investigate a file of unknown provenance.

FITS is also often used to store non-image data, such as spectra, photon lists, data cubes, or even structured data such as multi-table databases. A FITS file may contain several extensions, and each of these may contain a data object. For example, it is possible to store x-ray and infrared exposures in the same file.

This file format also sometimes uses FTS file extension or FIT file extension.

How to open fits file?

There are also some specialized FITS viewers that can open .fits files.

Some image viewers such as GIMP, Photoshop, XnView and IrfanView can generally read simple *.fits images, however are not able to interpret more complex files.

How to convert fits file?

Specialized viewers AVIS - FITS Viewer can convert .fits images to common bitmap files.

Suggested software to open fits file:

Associated software actions with the fits file

Open

Software applications that can open fits files:

AVIS - FITS Viewer (Microsoft Windows)

Affinity Photo (Multiplatform)

Edit

Software applications that can edit fits files:

Affinity Photo (Multiplatform)

Save

Software capable of saving fits files:

AVIS - FITS Viewer (Microsoft Windows)

View

Programs for viewing fits files:

XnView MP (Multiplatform)

GDAL (Multiplatform)

Convert

Software apps that convert fits files:

XnView MP (Multiplatform)

Picture Resize Free Online Images Converter (On-line services)

Import

Software apps that import fits files:

AVIS - FITS Viewer (Microsoft Windows)

PIPP (Microsoft Windows)

SAOImageDS9 (Microsoft Windows)

Bio-Formats (Multiplatform)

Affinity Photo (Multiplatform)

Export

Software apps that export fits files:

AVIS - FITS Viewer (Microsoft Windows)

PIPP (Microsoft Windows)

NASA PDS4 Tools (Microsoft Windows)

Software apps that print fits files:

XnView MP (Multiplatform)