How to convert STL to STEP
- Drop your
.stlabove (or several, or a 3MF, OBJ or GLB). - Keep STEP selected. Untick objects you don't need.
- Click Download STEP and open the file in your CAD program.
What you get — and what you don't
- A faceted solid. The STEP contains the same triangles as the mesh, written as planar faces with shared edges. Closed (watertight) meshes become solids; meshes with holes become surface bodies.
- Exact size in millimetres, one body per part, part names kept.
- No smooth surfaces. A curved mesh stays faceted: it is not reverse-engineered into cylinders and fillets. For a few edits (holes, cuts, adding a bracket) that is usually enough; for full parametric editing the model has to be redrawn.
The file was checked by importing it with OpenCascade, the geometry kernel behind FreeCAD.
Keep the mesh light
Every triangle becomes a CAD face, so dense meshes make big STEP files that CAD programs open slowly. Up to about 200,000 triangles are accepted; reduce larger meshes first (Decimate in Blender, Reduce in Meshmixer).
Frequently asked questions
Is STL to STP the same as STL to STEP?
Yes. .stp and .step are two extensions for the same format (ISO 10303-21). Rename the file if your program expects .stp.
Will the result be editable in Fusion 360 or SolidWorks?
It imports as a solid made of many flat faces. You can cut, extrude onto, measure and combine it; you can't change the original design parameters, because a mesh never had them.
Why does my STEP open as a surface, not a solid?
The mesh has holes or flipped triangles. Repair it (for example with your slicer's repair function or Meshmixer) and convert again.
Are my files uploaded?
No. Conversion runs in your browser; the file never leaves your computer.