STL to DWG converter options

An STL to DWG converter has to answer one question first: do you want a 2D drawing of the part or the 3D mesh inside a DWG? STL holds only triangles, so both routes go through a 3D program such as FreeCAD. This site does not read STL; it opens the DWG or DXF you produce so you can check it in the browser.

What is inside an STL file

STL describes a surface as thousands of flat triangles. There are no circles, no holes as features, no dimensions, and no units; a 50 mm cube and a 50 inch cube are the same file. A 3D printer only needs that surface, which is why STL is the default output of slicers and model sites.

CAD drawings need the opposite: true arcs, edges you can dimension, and a known scale. So the conversion either keeps the triangles (a mesh in a DWG, heavy and hard to edit) or extracts clean outlines from them (a 2D drawing, usually what people want).

Route 1: a 2D drawing from the STL with FreeCAD

1. Open FreeCAD and import the STL (File > Import). Note the size in the status bar to confirm the units, usually millimeters.
2. Switch to the Part workbench and run Part > Create shape from mesh. Then Part > Convert to solid and Part > Create a copy > Refine shape to merge coplanar triangles into faces.
3. Open the TechDraw workbench, insert a page, and add views of the solid: front, top, side.
4. Export the page as DXF (TechDraw > Export page as DXF).
5. If you need DWG, convert the DXF with the ODA File Converter; FreeCAD can also save DWG directly once that converter is installed and set in its preferences.

Curved surfaces come out as many short segments, because the mesh was faceted to begin with. Flat parts with straight edges convert very cleanly.

Route 2: keep the mesh in 3D

If the recipient wants the 3D shape, a mesh inside DWG is possible. FreeCAD or Blender can export the mesh to DXF as 3D faces, and recent AutoCAD releases import meshes through 3D tools that support it. Expect a large file: every triangle becomes an entity, so a detailed figurine can turn into a DWG of several hundred megabytes.

Reduce the triangle count first. Blender's Decimate modifier or MeshLab's simplification filters can cut a mesh to a tenth of its size with little visible change, which makes every later step faster.

For a part that needs real editing, the honest answer is to redraw it from measurements. A mesh-to-solid conversion is a starting point, not a parametric model.

Online STL to DWG converters

Online services convert simple STL files to DWG or DXF in one step. They usually export the projected outline or the raw triangles, with no control over which view you get. That can be enough for a quick outline of a bracket, but check the size afterwards: since STL has no units, the converter guesses.

The reverse direction, a DWG drawing to a printable STL, is covered on DWG to STL.

Check the result before you send it

Drop the DWG or DXF on dwgviewer.app. Measure an edge you know to confirm the scale. Then look at the entity count in the status bar: a few hundred entities for a simple part is normal, a few hundred thousand means the mesh came through as triangles. The file is read in the browser tab and is never uploaded.

The DWG converter overview lists other directions, and what is a DWG file covers versions if the recipient asks for an older one.

Frequently asked questions