Opening FCHK Files

The FCHK file type is primarily associated with Gaussian.

FCHK	File extension: FCHK
	File type:	data file

What is an FCHK file?

FCHK files mostly belong to Gaussian. The FCHK file is a Gaussian formatted checkpoint file that stores results from a quantum chemistry calculation.
This file uses a plain text structure to save important data such as molecular geometry, basis sets, and orbital information.
Key features include:

Data storage – It holds numeric and structural details needed for in-depth analysis.
Interoperability – It works with multiple tools, allowing further processing and visualization using programs like GaussView.
Editability – Even though it is text-based, the file has a strict format that should not be altered casually.

FilExt.com note: For more detailed information on how these files work and their use, please check the Gaussian website.

How to open an FCHK file

You need a suitable software like Gaussian to open an FCHK file. Without proper software you will receive a Windows message "How do you want to open this file?" or "Windows cannot open this file" or a similar Mac/iPhone/Android alert. If you cannot open your FCHK file correctly, try to right-click or long-press the file. Then click "Open with" and choose an application. You can also display a FCHK file directly in the browser:. Just drag the file onto this browser window and drop it.

Online FCHK Text Viewer

Choose your .fchk file to view

or drag and drop it here

Online File Viewer

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How to extract texts from FCHK files or capture a screenshot to PDF, JPG, DOCX, TXT, ...

If you want to extract texts from FCHK file or capture a screenshot, you can use our free Online FCHK File Viewer:

To do this, click the button "Choose your .fchk file to view" on this page.
After your file is opened in browser,
click "Save as..." in the menu.
Then choose the file format (e.g. JPG, PDF, DOCX, TXT, ...) you want.
Download the converted file.

Programs that open and convert FCHK files:

Gaussian
See the previous paragraphs to learn more about the main application. FCHK files are often referred to as Gaussian data files because this type of file is primarily created or used by this software.
Gaussian Checkpoint File by CambridgeSoft Corporation
The Mime types used with this association are: chemical/x-gaussian-checkpoint.

Technical Data for FCHK File Extension

File classification:

Data

Related files:

chk, gjf, com, f09, f08, xyz, mol, fch, c3d, gpt, log

Mime type:

chemical/x-gaussian-checkpoint

an fchk data file is a special file format and should only be edited and saved with the appropriate software.

How to solve problems with FCHK files

Associate the FCHK file extension with the correct application.
Update your software that should actually open data files. Because only the current version supports the latest FCHK file format. Search, therefore, e.g. on the manufacturer website after an available Gaussian update.
To make sure that your FCHK file is not corrupted or virus-infected, get the file again and scan it with Google's virustotal.com.
Click here to open your .FCHK file online - secure, fast, and no downloads needed.