Convert 3DM to OBJ
Convert 3DM to OBJ in your browser. The conversion runs on this page and the file never leaves your computer.
Result
Before you convert: what this keeps and what it destroys
Preserved
- The shape, to within the tessellation tolerance
- Overall dimensions and proportions
- Watertightness, where the input is watertight
- Colour
- Separate parts and their positions
Destroyed
- Exact curves and surfaces, replaced by triangles
- The feature tree and any parametric history
- A recorded unit: OBJ stores none
- Colour
- The separation between parts, merged into one body
Why people convert 3DM to OBJ
Rhino has deep roots in jewellery, footwear, marine and architecture, and this is the usual way work leaves it for a renderer or a mesh tool that does not speak 3DM.
Object names survive, so a model organised into named parts stays readable after the trip. What arrives is the render mesh Rhino saved with the file.
Two things to expect. Objects with no surface, which in a Rhino file often means construction curves, points, text and dimensions, have no render mesh and cannot be converted; the site counts them and tells you how many it skipped, so a partial model does not look complete. And colour is dropped, because the OBJ is written without a material library, which is a real loss when the source used layer colours to mean something.
What you get
You get a plain-text OBJ file you can open in an editor containing triangles. The reader tessellates supported surfaces or uses saved render meshes where required by the source format. Inspect curved faces at the intended output size. The triangle count depends on the model and the reader's meshing settings.
Carried across: object names, with positions applied to the geometry.
Not carried across by this conversion: a recorded unit, colour.
The conversion runs in your browser. Your file stays on your computer and is not uploaded.
What to check afterwards
- 3DM declares its unit in the file. Check the output dimensions in the receiving application, especially when its import settings can override the unit.
- The output keeps supported geometry and object names. The writer applies part transforms to the coordinates, without retaining the original transform hierarchy. It does not write material colours, texture coordinates or a companion material file.
- Curves become facets. 3DM stores exact surfaces, so a hole is a cylinder with a radius. OBJ stores triangles, so that cylinder becomes a many-sided prism. Look at curved faces in the result at the size you intend to make the part.
If you need something this conversion cannot give you
If the unit has to be unambiguous, convert to 3MF instead. It records the unit in the file, so nobody downstream has to assume millimetres and nobody has to scale by 25.4 after the fact.
If you need editable CAD geometry, don't convert at all. Open the 3DM file directly in FreeCAD, Fusion, Onshape or SolidWorks. Every mesh format destroys the exact surfaces, and no later conversion brings them back.
Going the other way
This site reads 3DM but does not write it. For the reverse conversion, use an application that can export 3DM.
How we know this conversion works
This pair was checked against 3 files from the test corpus on 2026-09-04. Each run parses its own output back in and compares the bounding box, the triangle count and, for closed solids, the volume against the input.
A pair that fails those checks doesn't get a page. That's why this site lists 120 conversions and not the several hundred a format-times-format grid would suggest.