Convert 3DM to glTF (Free)
Also converts STL, OBJ, GLB, PLY, USDZ, 3MF from the same file.
Runs in your browser. No upload, no signup, nothing to install.
Also from Innerscene: Circadian Lab, a free lighting calculator for room illuminance, melanopic EML, and glare.
How to convert 3DM to glTF
- 1
Open your .3dm file
Drag it onto the viewer above, or click "Open a 3DM File". Files up to 200 MB open directly; the parse runs in a worker so the page stays responsive.
- 2
Pick glTF separate (.gltf + .bin) in the Export menu
Click Export in the toolbar, then glTF (.gltf).
- 3
Download
The .gltf is written in the browser and saved straight to your downloads folder. No queue, no email, no watermark.
What survives the conversion
A file conversion is a translation, and formats do not carry the same things. Here is exactly what moves from 3DM into glTF, and what does not.
| Geometry | Reduced | 3DM stores exact B-rep solids and glTF stores triangles, so the surfaces are tessellated. Curved faces become faceted at the display tolerance, which is fine for visualization, printing and clash checking, but not for further parametric CAD work. |
|---|---|---|
| Colors and materials | Kept | glTF carries full PBR materials, which is at least what 3DM stores, so the colors come across. |
| Layers and structure | Kept | Layers survive as real layers in the glTF file, so you can still isolate and toggle them. |
| Units and scale | Kept | glTF stores an explicit unit, so the model opens at true size without rescaling. |
What the glTF writer emits: The GLB export unpacked into its two parts: a JSON `.gltf` with `buffers[0]` pointing at an external `${base}.bin` (the source file’s own base name), zipped together.
The source: Rhino 3D Model (.3dm)
Rhino meshes, NURBS surfaces and polysurfaces, SubD, curves, point clouds, layers with their colors, and the file unit system.
The target: glTF separate (.gltf + .bin) (.gltf)
The same glTF scene as the GLB export, as the loose JSON and binary files some pipelines expect instead of one packed file.
Opens in: Blender, Unity, Unreal Engine, model-viewer, any glTF-separate pipeline.
Your file never leaves your computer
Both the 3DM parser and the glTF writer are JavaScript and WebAssembly running in your own browser tab. There is no upload step, no server-side conversion queue, and no copy of your file anywhere but your machine. That matters for drawings under NDA, for client work, and for anything you would not email to a stranger.
Free to Use, No Signup
There are no accounts and no watermarks on this converter. If it saved you time, the one thing we ask is a mention: a post, a link from your blog or course page, or a reply to someone asking how to open a file.
Share it
Made something reusable? Add it to the Free Parts Library. Writing about it? Copy a link, badge or citation. Send us your post and we’ll feature it with a link to your site.
Hear about new formats
Occasional emails when the viewer learns a new format or gets a new tool.
Frequently asked questions
▶Is this 3DM to glTF converter free?
Yes. No signup, no watermark, no per-file limit and no paid tier. Innerscene.
▶Is my 3DM file uploaded anywhere?
No. The file is read with the browser file API and converted in the same tab. Nothing is sent to a server unless you explicitly click Share, which is a separate, opt-in feature.
▶Will my colors and materials survive the glTF export?
glTF carries full PBR materials, which is at least what 3DM stores, so the colors come across.
▶Do layers and named parts carry into the glTF file?
Layers survive as real layers in the glTF file, so you can still isolate and toggle them.
▶Will the glTF open at the right size?
glTF stores an explicit unit, so the model opens at true size without rescaling.
▶How large a 3DM file can I convert?
Up to 200 MB, and the ceiling adapts to how much memory your device reports. The conversion runs on your own hardware, so a desktop with plenty of RAM will handle more than a phone.
▶Can I convert glTF back to 3DM?
Yes, the other direction works too. Bear in mind that anything the first conversion dropped is not restored by converting back. glTF → 3DM
▶Which browsers does it work in?
Chrome, Edge, Firefox and Safari, on Windows, macOS, Linux, iOS and Android. No plugin and no extension.
Convert 3DM to something else
Save Rhino as an older version
Older software cannot open files saved by newer versions. These save a copy in the version the other side needs.
Convert something else to glTF
Or start from the universal 3D viewer.