Convert SLDPRT to 3MF
Free, in your browser, with nothing uploaded. Drop your .sldprt file in and take the .3mf away.
Drop your SLDPRT file here
.sldprt in, .3mf out
Choose filesNothing is uploaded No account, no email No file size limit
How to convert SLDPRT to 3MF
- 01
Add your .sldprt file
Drag your SolidWorks Part file onto the drop zone, or click it to browse. Nothing is uploaded: it is read where it already sits.
- 02
Check the preview
The model is parsed on your machine and drawn in the viewport, so a wrong axis or a missing texture shows up before you commit rather than downstream.
- 03
Save the .3mf file
Press convert. The 3D Manufacturing Format file is written in the tab and lands in your downloads folder. No link, no expiry, no account.
What carries over, and what does not
A format conversion is a translation, and translations lose things. Here is what actually happens when an SLDPRT file becomes a 3MF file.
| Data | SLDPRT | 3MF | Survives |
|---|---|---|---|
| Geometry | Yes | Yes | Yes |
| Materials & colour | No | Yes | n/a |
| Texture maps | No | Yes | n/a |
| Animation & rigs | No | No | n/a |
| Scene hierarchy | Yes | Yes | Yes |
This is a comparatively lossless pairing: 2 of the five categories above are supported by both formats, so most of what is in your SLDPRT file has somewhere to go in the 3MF file.
About SolidWorks Part
A .sldprt holds its solid twice over. The exact one is a Parasolid XT stream, a commercial kernel format that needs a NURBS engine to turn into triangles, and that is the part nobody can read. The other is the tessellation SolidWorks caches so it can draw a part in lightweight mode without rebuilding it, and that one is a mesh: per face, a list of triangle strips with float32 positions in metres, unit normals and texture coordinates. That is what we read. Files from 2014 and earlier are OLE2 compound documents whose larger streams are chains of zlib blocks; 2015 and later use a container of SolidWorks' own, with stream names written with the nibbles of every byte swapped. Both open here, along with the properties, the configurations and the preview image the file carries of itself. The mesh is at the deviation the part was saved with, which is the same surface SolidWorks shows you; if you need the exact analytic surfaces, export STEP.
Commonly seen in: SolidWorks. More on the SLDPRT format page.
About 3D Manufacturing Format
3MF is what STL should have been. Built by the 3MF Consortium as a zipped XML package, it records units, colours, materials, per-object print settings and the arrangement on the build plate, and it defines what a valid manifold mesh is so slicers stop guessing. Bambu Studio, PrusaSlicer and Cura all treat it as a first-class project format.
Commonly seen in: Bambu Studio, PrusaSlicer, Cura, Windows 3D Builder, Fusion 360. More on the 3MF format page.
How the conversion works
When you drop a file in, the bytes are handed to a parser compiled to run in your browser. The SLDPRT data is decoded into an in-memory scene graph of meshes, materials and transforms, which is what the preview is drawing. Pressing convert walks that scene graph back out through a 3MF writer and hands you the resulting bytes as a download.
The whole round trip is local. The page itself is static: it is delivered once and then does its work offline. That is why the privacy claim is checkable rather than a promise.
SLDPRT to 3MF: common questions
Is my SLDPRT file uploaded anywhere?
No. The file is read by code running inside this browser tab and never crosses the network. You can prove it by disconnecting from the internet before you convert, the page keeps working, or by watching the Network tab in your browser's developer tools while you drop a file in.
How large an SLDPRT file can I convert?
There is no server-side limit because there is no server. The practical ceiling is your own machine's memory: a browser tab can usually handle models up to a few hundred megabytes. Very dense scans or scenes with millions of triangles will take a few seconds and a lot of RAM.
Why does my converted 3MF file look untextured?
Because this writer leaves them out. 3MF references an image by filename rather than storing it inside the file, so the images would have to travel separately and land where the file expects them, which is how a converted model arrives broken. Convert to GLB, FBX or USDZ instead if the textures need to stay with the model.
Does it cost anything?
No. There is no fee, no account, no watermark and no per-file limit. Since the conversion runs on your hardware rather than ours, serving this page costs about as much as serving a blog post.
Does it work on a Mac, on Windows or on a phone?
All of them. There is nothing to install: any browser with WebGL 2 will do, which covers current Chrome, Edge, Firefox and Safari on desktop, and Safari and Chrome on mobile. A phone has less memory than a laptop, so a very heavy scene may be the one thing it cannot finish.
Related conversions
Other things to do with the same file.
From SLDPRT:
Other ways to get to 3MF:
Or do something else with it: