OFF File Format (.off)
An OFF file is plain text written for the Geomview viewer built at the University of Minnesota's Geometry Center, starting with the word OFF and a line giving the vertex and face counts before listing each vertex's coordinates and each face's vertex indices in order.
OFF at a glance#
| Full name | Object File Format |
|---|---|
| File extension | .off |
| Category | 3D Models |
| Developer | The Geometry Center, University of Minnesota |
| Compression | Uncompressed |
| FileFlip support | FileFlip reads this format but does not write it |
What a .off file can hold#
These are the things a OFF file either supports or does not, and they are what decides whether a conversion keeps everything or quietly drops something.
| Human readable | Yes |
|---|---|
| Comments | Yes |
Strengths and limitations of OFF#
What OFF does well
- About as simple a mesh format as exists, which makes it easy to generate and parse from a research script
- Faces can have any number of vertices, not just triangles or quads
- Optional per-vertex or per-face RGBA colour without any extra structure beyond the base format
Where OFF falls short
- No materials, textures, normals or units, only raw geometry and optional colour
- No skeleton or animation support of any kind, since it was never meant for anything but a static shape
- Mainstream 3D and CAD software mostly doesn't read it; support is concentrated in research and geometry-processing tools
Use OFF when a mesh needs to move between computational geometry tools or research code that already expects the format.
Convert OFF to OBJ or STL when the mesh needs to open in mainstream 3D software, since OFF support outside academic tools is limited.
How to open a .off file#
A .off file opens in the programs below, grouped by the platform you are on. If you would rather not install anything, FileFlip converts OFF into a format your machine already opens, and it does it in the browser tab rather than on a server.
| Platform | Programs that open it |
|---|---|
| Windows | MeshLab, CloudCompare |
| macOS | MeshLab, CloudCompare |
| Linux | MeshLab, Geomview |
| Web | FileFlip |
OFF questions people ask#
What is an OFF file?
An OFF file is a minimal 3D mesh format: a vertex count, a face count, a list of vertex coordinates and a list of faces given as vertex indices, with nothing else. It comes from Geomview, the visualisation tool built at the University of Minnesota's Geometry Center, and shows up throughout computational geometry research and teaching material.
What software opens OFF files?
MeshLab and Geomview both open OFF files directly, and most computational geometry libraries such as CGAL can read and write it. Outside of research and mesh-processing tools, general-purpose 3D software rarely supports it natively.
Does an OFF file support color?
Yes, an OFF file can carry an optional RGBA colour value on each vertex or each face, appended right after its coordinates or indices. It's the one piece of surface information the format supports beyond raw geometry.
Converting OFF files#
Convert OFF to another format
FileFlip does not write .off files, so nothing on the site converts into this format. It works as a source only.
Every conversion runs inside your browser. The file is read from your disk, the work happens on your own machine, and nothing is uploaded. How FileFlip works names the engine behind each family and how to verify that for yourself.