Convert SolidWorks files to STL
SolidWorks writes STL from the Save As dialog rather than from an Export menu, which is the first thing people miss. The settings behind the Options button are the second.
We cannot read SolidWorks files of any kind — .sldprt or .sldasm. The formats are closed and undocumented, so no browser tool will ever open one. The export has to happen in SolidWorks, or the sender has to give you a STEP file instead.
The short version
File, Save As, then choose STL (*.stl) as the file type. An Options button appears; press it. Set Resolution to Custom, deviation tolerance to about 0.01 mm and angle tolerance to 5 degrees for a part up to 100 mm. Check the unit is Millimeters and the output is Binary. Then save.
That is the whole process for a part. An assembly has an extra decision — whether you want one STL for the whole thing or one per component — and there is a separate page on this site covering that.
The full explanation of what those tolerance settings do to a printed surface, and what to do when you have no SolidWorks licence, is on the SLDPRT to STL page.
Where we can actually help
Once you have the STL, the rest runs here in your browser — including converting it to 3MF so the units travel with the file.
Questions
- Where is the STL export in SolidWorks?
- Under File, Save As, not File, Export. Choose STL (*.stl) from the Save as type list and an Options button appears in the dialog.
- I do not have SolidWorks. What are my options?
- Ask whoever sent the file for a STEP export instead — it takes them fifteen seconds and STEP opens in FreeCAD, Fusion 360, Onshape and every free viewer. eDrawings can sometimes export STL from a .sldprt, but only if the file was saved with that permission enabled.
Where to go next
Related guides
Tools that do part of this here
About these formats
Checked against current software versions on 2026-09-11