CUBE File

What are CUBE files and how to open them

Are you having problems opening a CUBE file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your CUBE files.

What is a CUBE file?

CUBE files have multiple uses, and Cube LUT format is one of them. Read more about the other uses further down the page.

Cube LUT format

These CUBE files describe look-up tables, which are a way to change the color of an image's color representation from one color to another.

How to open CUBE files

Important: Different programs may use files with the CUBE file extension for different purposes, so unless you are sure which format your CUBE file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested four different CUBE openers which you will find listed below.

Last updated: September 19, 2026

All known file formats using extension .CUBE

While Cube LUT format is a popular type of CUBE-file, we know of 3 different uses of the .CUBE file extension. Different software may use files with the same extension for different types of data.

Gaussian Cube Data

Gaussian Cube Data format stores molecular geometry plus volumetric grid data generated during electronic structure calculations. It is created by Gaussian (and related computational chemistry tools) through utilities like cubegen. Files in this format hold values such as electron density or molecular orbital amplitudes sampled over a three-dimensional grid covering a region of interest around the molecule.

The format is plain text. It begins with two comment lines serving as human-readable labels or headers. Then follows a line with the number of atoms and coordinates of the origin of the volumetric grid. Three lines follow, each specifying the number of voxels (grid points) along one Cartesian axis plus that axis's step vector, allowing for non-cubic, non-orthogonal, or sheared grids. After that there is one line per atom giving atomic number, (formal) charge, and xyz coordinates of the atom centers. The volumetric data is provided next: for every voxel one scalar value (float) arranged in nested loops, usually with x varying slowest and z fastest, with whitespace separating values, and newlines every sixth value along the innermost direction.

All numeric values are in atomic units: lengths (grid step vectors, origin) in Bohrs (or Angstroms if negative voxel counts), and volumetric values (densities, orbital values) in appropriate quantum-mechanical units per calculation program. Because the file is text-based, parsers must allow for flexible whitespace and for varying line breaks in the volumetric section.

Byte signature includes the ASCII string "CPMDCUBEFILE" at the very start (offset 0) to identify this format.

Lightworks Cube LUT

We know that one CUBE format is Lightworks Cube LUT. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

Various apps that use files with this extension

These apps are known to open certain types of CUBE files. Remember, different programs may use CUBE files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about CUBE file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.