STL to STEP — open an STL in Fusion, SolidWorks or FreeCAD
Convert STL to STEP as a closed faceted solid: flat areas joined into single faces, so walls and holes can be measured and edited in CAD. In your browser, nothing uploaded, no account.
Saves model files for your slicer, never printer code. Opened and sliced in PrusaSlicer, OrcaSlicer, Bambu Studio and Cura.
About this conversion
An STL is only triangles; CAD wants faces. Neighbouring triangles that lie in one plane are joined into one face — a box becomes six faces, a flat plate with a hole becomes one face with a hole — and the result is written as one closed solid, which Fusion, SolidWorks, Onshape and FreeCAD open as a body you can measure, cut and extend. Curved surfaces stay faceted: a cylinder comes out as many narrow flat faces, not a true cylinder. A model with holes has to be repaired first, because CAD only takes a closed solid.
Just want to look inside it?
The same tool without converting anything: open the file and read it.
The same model, other ways
The model stays open after it is read, so the format is picked at the end: the same model can leave here as 3MF (.3mf) or OBJ (.obj). Before that you can repair it, cut it, make it smaller or combine it with another one.
Questions
- Will curves become real curves?
- No. Flat areas become real flat faces; curved areas stay as many small flat faces. That is enough to measure, cut and add features in CAD, but a hole will not be recognised as a cylinder.
- Is it checked?
- Every STEP written here is read back in our tests by OpenCascade, the kernel inside FreeCAD and PrusaSlicer: same volume, same place, one closed solid.