Opening FIT files

Have a problem opening a .FIT file? We collect information about file formats and can explain what FIT files are. Additionally we recommend software suitable for opening or converting such files.

What is the .FIT file type?

The primary role of the .fit filename extension binds it with the FITS Image File (.fit, .fits, .fts) file type associated with the Flexible Image Transport System (FITS). FITS is a lossless image format developed by the FITS Working Group of the International Astronomical Union (IAU) for astronomy and space exploration.

The .fit file is an astronomic observation image in the FITS format. Besides the detailed ASCII metadata, it may include a series of images acquired from different sources and in different spectral ranges as well as store multi-dimensional data arrays. FITS files are conventionally denoted with the .fit extension, although other extensions (.fits, .fts) are used, too.

Certain simple FITS images can be directly opened in general-purpose bitmap graphics editors and viewers, while complex .fit files usually require special handling in scientific software, often through custom-written parsers.

Alternatively, the .fit extension denotes the Garmin Activity File (.fit) file type, with reference to the Flexible and Interoperable Data Transfer (FIT) format used by Garmin Edge, Forerunner, and Fenix series gadgets. Here, the .fit file ("," "," etc.) serves as a log for multiple fitness activities (swimming, jogging, cycling, etc.), combining GPS tracks with speed, heart rate and energy workout figures. Such logs can be downloaded for viewing and analysis using Garmin's official Training Center software (Microsoft Windows/Apple Mac OS X).

A detailed specification of the FIT format and reference tools are provided in the FIT SDK (Dynastream Innovations Inc.). Besides, several third-party tools allow to repair corrupted FIT files, manipulate their records and data sections, as well as perform conversion to/from text-based formats (CSV).

Software to open or convert FIT files

You can open FIT files with the following programs:
FITS Liberator
FITS Liberator by ESO/ESA/NASA
MaxIm DL
MaxIm DL by Diffraction Limited

Popular formats