SolidWorks Part .sldprt
SolidWorks parts, read from the tessellation SolidWorks itself draws with.
What an .sldprt file holds
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.
| Data | Stored in SLDPRT |
|---|---|
| Geometry | Yes |
| Materials and colour | No |
| Texture maps | No |
| Animation and rigs | No |
| Scene hierarchy | Yes |
| Read here | Yes |
| Written here | No |
Tested against a real file
The last sweep loaded top-piece.SLDPRT from Wilson lab open-hardware drives with its 2 sidecar files through the viewer on this site: 864 triangles across 12 meshes and 1 materials, in 2.0 seconds. Every format's result is on the test results page, run 2026-09-08.
Convert SLDPRT to another format
Every pairing has a page saying what survives the trip.
Other things to do with an .sldprt file
Questions about SLDPRT
How do I open an .sldprt file?
Drop it into the viewer on this site and it opens in the browser, with the scene tree, the materials and the mesh statistics. Nothing is uploaded. If you want it in another program instead, convert it to GLB, which almost everything reads.
Is SLDPRT a good format to archive in?
SLDPRT stores geometry, scene hierarchy. Anything outside that list will not be in the file at all, so archive the original alongside it if the surfacing or the rig matters.
Does converting SLDPRT lose quality?
Geometry is copied vertex for vertex, so the shape does not degrade. What gets lost is whatever the target format has no field for: convert to STL and the materials go, convert to OBJ and the animation goes. The comparison table on each converter page says exactly which.
Written up on the blog
Formats that hold the same things
Or go back to the full format reference.