The short answer
A .3dm file is a binary 3D model file created by Rhinoceros (Rhino). It's the industry-standard format for NURBS modeling in architecture, jewelry, industrial design and marine design. Every .3dm file is written with the open-source OpenNURBS toolkit maintained by Robert McNeel & Associates, so third-party apps can read and write them without a Rhino license.
What's inside a .3dm file?
Geometry
NURBS surfaces & curves, SubD, meshes, points, extrusions — everything Rhino models.
Layers & blocks
Full layer tree, block definitions and instances, groups, and object attributes.
Materials & rendering
Materials, textures, environments, render meshes and viewport render settings.
Metadata
Annotations, dimensions, notes, plugin user data, document units and tolerances.
.3dm versions explained
Every Rhino release bumps the OpenNURBS archive version whenever new object types are introduced. The archive version tells Rhino whether it can open the file.
| Rhino version | Archive | Released | Key additions |
|---|---|---|---|
| Rhino 8 | v80 | 2023 | PushPull history, ShrinkWrap, Content Filler, revised annotations |
| Rhino 7 | v70 | 2021 | SubD geometry, QuadRemesh, new PDF export |
| Rhino 6 | v60 | 2018 | Grasshopper baked in, new display modes |
| Rhino 5 | v50 | 2012 | 64-bit engine, Gumball, improved surface tools |
| Rhino 4 | v40 | 2007 | Clipping planes, new rendering |
| Rhino 3 | v30 | 2004 | History recording |
| Rhino 2 | v20 | 2001 | First OpenNURBS release |
Backward-compatible, not forward. Rhino 8 opens every older .3dm file. Rhino 7 refuses Rhino 8 files. The fix is to convert the newer file to the older archive version — that's what this tool does.
How to open a .3dm file
- • Rhinoceros 3D — the native app. Opens every version at or below its own.
- • Rhino Viewer — free viewer from McNeel; opens any .3dm for inspection.
- • Convert to a neutral format — export to STEP, IGES, OBJ or STL to open in Fusion 360, SolidWorks, Blender, Maya, etc.
- • Convert to an older Rhino version — if your Rhino refuses the file, drop it here and pick your target version.
Got a .3dm file you can't open?
99% of the time it's a version mismatch. Drop the file below — we detect the version and convert it to the one your Rhino supports.
We'll pick the highest compatible older version automatically after upload.