Format Guide
OFF File Format (.off)
The minimal ASCII mesh format — clean, dependency-free polygon geometry for research and processing tools.
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Where this format fits
Your file
Solid CAD
- STEP
- IGES
- BREP
Meshes
- STL
- OBJ
- 3MF
- PLY
- glTF
- GLB
- FBX
- DAE
- X3D
- OFF
- AMF
3D faces in drawings and scenes
- DXF
- DWG
- USD
What you get
3D printing
- STL
- 3MF
- OBJ
- PLY
Web, AR and games
- glTF
- GLB
- FBX
- DAE
Viewers and archives
- VRML
- X3D
- OFF
CAD exchange
- STEP
- IGES
- BREP
Solid CAD (STEP, IGES, BREP) can become a mesh or another solid format. A mesh converts to other meshes. Dashed formats (DXF, DWG, AMF, USD) can be read but not written. VRML reads .wrl, .vrml and gzipped .wrz files and writes .wrl.
- Convert a 2D-only DWG or DXF drawing. It needs 3D faces.
- Turn a mesh (STL, OBJ, 3MF) back into STEP, IGES or BREP.
- Read native SolidWorks, Inventor or CATIA files. Export STEP or IGES from that program first.
| Extension | .off |
|---|---|
| Full name | Object File Format |
| Geometry type | Polygon mesh (triangles and polygons) |
| Variants | OFF (plain), COFF (color), NOFF (normals), CNOFF (color+normals) |
| Open standard | Yes |
| Supports color | COFF variant only |
| Supports normals | NOFF variant only |
| Encoding | ASCII text |
What is an OFF file?
OFF (Object File Format) is a minimal ASCII text format for representing polygon meshes. An OFF file starts with the keyword 'OFF', followed by counts of vertices, faces, and edges, then vertex coordinates, and finally faces (each defined by a vertex count and indices). Optional color variants (COFF for color, NOFF for normals) add per-vertex attributes. OFF was popularized by the Princeton Shape Benchmark and Geomview visualization software, becoming a de facto standard for distributing polygon mesh test datasets in computational geometry research. It is intentionally simple — no materials, no textures, no hierarchy — just raw polygon geometry.
Common Uses of OFF Files
Academic geometry processing libraries (CGAL, libigl, OpenMesh) use OFF as a common test format. Princeton Shape Benchmark and similar datasets are distributed as OFF files.
OFF is used in mesh processing pipelines where a simple, dependency-free, human-readable format is preferred between preprocessing scripts and mesh analysis tools.
Geomview, the interactive 3D viewer from the Geometry Center, uses OFF as its native format and drove adoption in the academic visualization community.
Software Support
MeshLab, Geomview, CGAL, libigl, OpenMesh, Blender (via import plugin), and 3D CAD Converter.
Convert This Format
Commonly converted to STL for 3D printing, to OBJ for rendering, or to PLY for datasets requiring per-vertex attributes. Mesh repair is often needed before printing OFF files.
How to Convert OFF to OBJ, STL or PLY
OFF is a minimal academic mesh format that few mainstream tools read. 3D CAD Converter opens .off files directly and exports them to widely supported mesh formats in three steps.
Add your OFF files
Drag a single .off file or an entire folder into the app. Plain OFF and the COFF/NOFF color and normal variants are all read.
Pick an output format
Choose OBJ for broad compatibility, STL for 3D printing, or PLY when you need per-vertex attributes. Set units and tessellation if required.
Click Convert
The whole batch runs locally with a progress bar and ETA. Nothing is uploaded to the cloud.
Prefer the command line? The same conversions run from the CLI for scripting and automation:
# Convert an OFF mesh to OBJ for broad compatibility cadconvert convert model.off -o model.obj # Convert an OFF mesh to STL for 3D printing cadconvert convert model.off -o model.stl # Convert an OFF mesh to PLY for per-vertex data cadconvert convert model.off -o model.ply # Batch-convert a whole folder of OFF files to OBJ cadconvert batch ./in -o ./out -f obj -r # Keep half the triangles of a dense mesh cadconvert convert model.off -o model_light.stl --decimate 0.5
OFF is both an import and an export format. Use --units to set the scale and --decimate to reduce the triangle count on export.
OFF: the simple geometry-processing format
OFF is deliberately minimal — just vertices and faces in plain ASCII, with no materials, textures or scene hierarchy. That simplicity is its strength in computational-geometry research: it is trivial to parse, easy to generate from a script, and human-readable for debugging. It is the format of the Princeton Shape Benchmark and the native format of Geomview, so it shows up constantly in academic mesh datasets and processing pipelines.
Common OFF Issues (and How to Fix Them)
Many 3D tools and viewers cannot open OFF, and Blender needs an import plugin. Converting OFF to OBJ or STL makes the mesh usable almost everywhere — 3D CAD Converter reads OFF natively, no plugin required.
Plain OFF stores geometry only; only the COFF/NOFF variants carry color or normals. If you need color or materials downstream, convert to OBJ, PLY or glTF, which support per-vertex or material color.
Because OFF is plain text, high-resolution meshes produce very large, slow-to-load files. Converting to binary STL or binary PLY dramatically reduces file size and load time for big models.
OFF File Format — FAQ
What is an .off file?
An .off file is an OFF file — the Object File Format, a minimal ASCII format for polygon meshes. It begins with the keyword OFF, then vertex, face and edge counts, then vertex coordinates and face indices. Popularized by the Princeton Shape Benchmark and Geomview, it stores plain geometry only — no materials, textures or hierarchy.
How do I open an OFF file without MeshLab or Blender?
OFF is a niche academic format that many viewers do not read, and Blender needs a plugin. 3D CAD Converter opens .off files directly and exports them to OBJ, STL, PLY, glTF and 12+ formats in batch — no plugin required. Drop a file or a folder, pick a format and click Convert.
How do I convert OFF to OBJ?
Open the .off in 3D CAD Converter and choose OBJ, or run cadconvert convert model.off -o model.obj. OBJ is far more widely supported than OFF, so converting makes the mesh usable in almost any 3D tool. Use cadconvert batch ./in -o ./out -f obj -r to convert a whole folder at once.
Can I convert OFF for free?
Yes. 3D CAD Converter has a free trial that converts OFF to OBJ, STL, PLY, glTF and more, including full batch folders, with control over units and tessellation. It covers 10 conversions at full quality with no end date, and no credit card is required on Windows 10 or 11.