What Is a .cube File? The 3D LUT Format Explained
The .cube file is the de-facto standard container for 3D LUTs, originally specified by Adobe/IRIDAS. If you've ever downloaded a “cinematic LUT pack”, you almost certainly received a folder of .cube files.
Despite carrying sophisticated color science, a .cube file is astonishingly simple: it's plain text you can open in any editor.
Inside a .cube file
A .cube file starts with a tiny header and then lists color values, three floating-point numbers (red, green, blue, each 0–1) per line:
TITLE names the look. LUT_3D_SIZE declares the grid resolution — 33 means 33 steps per channel, so 33³ = 35,937 data lines follow. The lines run through every grid coordinate with red varying fastest, then green, then blue. DOMAIN_MIN and DOMAIN_MAX (usually 0 and 1) declare the input range.
- ·TITLE "My Cinematic Look"
- ·LUT_3D_SIZE 33
- ·DOMAIN_MIN 0.0 0.0 0.0
- ·DOMAIN_MAX 1.0 1.0 1.0
- ·0.023529 0.043137 0.070588 ← the new color for pure black
- ·… 35,936 more lines …
Where .cube files work
Practically everywhere color is graded: Adobe Premiere Pro and After Effects (Lumetri), DaVinci Resolve, Final Cut Pro, Photoshop (Color Lookup adjustment layer), Affinity Photo, OBS for live streams, and many camera monitors for on-set preview.
Notably absent: Lightroom, which uses its own profile and preset formats instead — one reason it's useful to have a look in both .xmp and .cube form.
Common sizes and quality
17-point LUTs are compact and fine for technical transforms. 33 points is the sweet spot for creative looks — smooth gradients at ~1 MB of text. 65-point files exist for high-precision pipeline work but are rarely necessary for creative grading.
Frequently asked questions
How do I open a .cube file?
To inspect it, any text editor works. To use it, load it into your editor's LUT slot — e.g. Lumetri's Creative tab in Premiere, or a Color Lookup layer in Photoshop. In RawCut, drop it into the Sandbox to preview it on your own photo instantly.
Are .cube files safe to download?
Yes — they are pure text data with no executable content. The worst a bad LUT can do is make your footage look ugly.
Can I convert a Lightroom preset to a .cube LUT?
Not directly in Lightroom. RawCut does exactly this: it renders the preset's global color transformation and bakes it into a standard .cube file you can use in video editors.
Build or borrow a look in the Sandbox, then export it as a Premiere/Resolve-ready .cube in one click.
Export your own .cube