What is the OFF file format?
An .off file is a plain-text (or optionally binary) 3D polygon mesh in the Object File Format, originating at DEC Systems Research Center around 1986 and widely adopted through the Geomview visualization tool developed at the University of Minnesota Geometry Center in the early 1990s.
The format is intentionally minimal. The first line contains the keyword OFF (or a variant such as COFF, NOFF, or CNOFF), the second line declares vertex, face, and edge counts, and subsequent lines list vertex coordinates followed by face definitions. Faces can be arbitrary polygons - not limited to triangles - distinguishing OFF from .STL, which requires full triangulation.
Variant header keywords extend the base format:
COFF- per-vertex or per-face RGBA colorNOFF- per-vertex surface normalsCNOFF- color plus normals combined4OFF- 4D homogeneous geometry- Binary OFF - big-endian binary encoding of the same structure
OFF does not support embedded materials, textures (in the standard form), animations, or scene graphs, limiting its use in production pipelines. It remains the preferred format for computational geometry research and academic datasets such as the Princeton Shape Benchmark and Thingi10K. Tools such as MeshLab can convert .off meshes to more widely supported formats including .OBJ and .PLY.
Security & safety
RISK: LOWPlain ASCII text format (standard OFF); no embedded code, macros, or executables. Binary OFF is also pure data. No known exploit vectors.
Format details
in a nutshellPrograms that open OFF files
Windows3 apps
MeshLab
Open-source File → Import Mesh → select .off file. Supports all OFF variants including COFF/NOFF. View, edit, convert. 
Blender
Open-source File → Import → Stanford PLY / OFF (ensure 'Import OFF' add-on is enabled in Preferences → Add-ons). Converts to Blender mesh for editing. 
Open3D
Open-source Python: o3d.io.read_triangle_mesh('file.off') - programmatic import for research/scripting workflows. 
macOS1 app
Linux1 app
Technical details
deep spec| Encoding | ASCII text (standard); big-endian binary (binary variant) |
| File signature | First line must be OFF (or variant prefix: COFF, NOFF, CNOFF, 4OFF, ST); binary variant adds " BINARY" after OFF |
| Header structure | Line 1: keyword; line 2: vertex_count face_count edge_count (edge_count may be 0 and is ignored) |
| Vertex format | One vertex per line as x y z (3D) or x y z w (4D); optional per-vertex RGBA and/or normals in COFF/NOFF/CNOFF variants |
| Face format | Each line starts with vertex count followed by 0-based vertex indices; supports arbitrary polygon faces, not limited to triangles |
| Color support | 24-bit RGB or 32-bit RGBA, optionally per vertex (COFF/CNOFF) or per face |
| Normal support | Per-vertex surface normals via NOFF or CNOFF variant header |
| Typical file size | 1 KB - 500 MB (research and scan meshes can be very large) |
| Format variants | OFF (geometry only), COFF (color), NOFF (normals), CNOFF (color + normals), 4OFF (4D), ST (texture UVs), binary OFF |
| Associated OS | Linux, macOS, Windows (cross-platform; dominant in research and academic environments) |
| Limitations | No embedded materials, textures (standard variant), animations, or scene graphs |
| Index base | Vertex indices in face records are 0-based |
| Released | ~1986 (DEC SRC); widely adopted via Geomview ~1992 |
| Latest version | No versioned spec; format stable since early 1990s. Extensions: COFF (color), NOFF (normals), CNOFF (color+normals), ST (texture), binary variants. |
| Open standard | Yes · royalty-free |
| Specification | people.sc.fsu.edu |
OFF conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about OFF files.
