Convert STL to 3DM (Free)
Also converts OBJ, GLB, PLY, USDZ, 3MF, WRL 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 STL to 3DM
- 1
Open your .stl file
Drag it onto the viewer above, or click "Open an STL File". Files up to 200 MB open directly; the parse runs in a worker so the page stays responsive.
- 2
Pick Rhino 3D Model in the Export menu
Click Export in the toolbar, then 3DM (.3dm).
- 3
Download
The .3dm 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 STL into 3DM, and what does not.
| Geometry | Kept | Both formats store triangle meshes, so the shape transfers directly. |
|---|---|---|
| Colors and materials | N/A | STL files carry no color, so the 3DM comes out in the viewer’s default material. You can color it in the destination application. |
| Units and scale | Kept | 3DM stores an explicit unit. STL does not, so the size is taken from how the viewer read the file. Check the scale once on import. |
What the 3DM writer emits: openNURBS meshes, point clouds with per-point color and capped line curves, on real layers with their colors, Z-up, with the model unit system set from the source file so Rhino reads true size.
The source: Stereolithography (.stl)
A single triangle soup. STL stores no color, no units, no parts and no layers, only the surface.
The target: Rhino 3D Model (.3dm)
Rhino native, written at archive version 5 so it opens in Rhino 5 from 2012 through current.
Opens in: Rhino 5 and later, Grasshopper, Matrix, RhinoGold.
Your file never leaves your computer
Both the STL parser and the 3DM 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.
Frequently asked questions
▶Is this STL to 3DM converter free?
Yes. No signup, no watermark, no per-file limit and no paid tier. Innerscene.
▶Is my STL 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 3DM export?
STL files carry no color, so the 3DM comes out in the viewer’s default material. You can color it in the destination application.
▶Will the 3DM open at the right size?
3DM stores an explicit unit. STL does not, so the size is taken from how the viewer read the file. Check the scale once on import.
▶How large an STL 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 3DM back to STL?
Yes, the other direction works too. Bear in mind that anything the first conversion dropped is not restored by converting back. 3DM → STL
▶Which browsers does it work in?
Chrome, Edge, Firefox and Safari, on Windows, macOS, Linux, iOS and Android. No plugin and no extension.
Convert STL to something else
Convert something else to 3DM
Or start from the universal 3D viewer.