Convert DWG to STEP (STP)

DWG to STEP conversion works when the DWG contains 3D solids: export them from a CAD program that writes STEP. A flat 2D drawing has nothing for STEP to describe, so it has to be modeled in 3D first. This site does not write STEP; it opens the DWG in your browser so you can see whether you have a 2D drawing or a 3D model.

Find out what your DWG contains

STEP is a format for 3D solid geometry, the kind used to exchange parts between mechanical CAD programs. A DWG can hold 3D solids, but most DWG files in circulation are 2D: plans, sections, part drawings with dimensions. Converting a 2D DWG to STEP gives an empty file or a set of flat wires that no CAD program will treat as a part.

Open the DWG and look at it. Dimensions, title block, and several views of the same part arranged on a sheet mean it is a 2D drawing. A single object with no annotation that someone describes as "the model" may be 3D; the sender can confirm.

If the DWG has 3D solids

Use a program that reads DWG solids and writes STEP:

• Mechanical toolsets for AutoCAD include a STEP export (STEPOUT). Plain AutoCAD exports ACIS .sat instead, which most mechanical CAD programs can import and re-save as STEP.
• BricsCAD exports STEP from its 3D workspace.
• Inventor, SolidWorks, and Fusion import DWG solids and save them as STEP.
• FreeCAD reads DWG through the ODA File Converter and exports STEP from File > Export, though complex ACIS solids sometimes come in as surfaces.

After export, open the STEP file in a second program and check that it arrived as a solid, not a collection of faces.

If the DWG is 2D: build the part in FreeCAD

1. Open the DWG in FreeCAD (with the ODA File Converter set up in Preferences > Import-Export > DWG). The drawing comes in as 2D wires.
2. Select the outline of the profile you want to turn into a part, such as the top view of a plate.
3. In the Part workbench use Part > Extrude, set the thickness, and tick "Create solid".
4. Add holes and pockets the same way: extrude their profiles and subtract them with Part > Boolean > Cut.
5. Select the finished solid and use File > Export, type STEP with colors.

This works for flat, prismatic parts. Anything with fillets, draft angles, or curved surfaces needs to be modeled properly from the drawing's dimensions; no converter can guess the third dimension of a sectioned casting.

Why online DWG to STP converters disappoint

Online converters translate whatever geometry they find. For a 2D DWG they write a STEP file with wires or nothing at all, and the receiving CAD program shows an empty part. For a 3D DWG they may work, but the file goes to their server, and product designs usually should not.

The opposite direction is much more common: STEP to DWG explains how to make a drawing from a 3D part.

Check the DWG in the browser first

Drop the file on dwgviewer.app before installing anything. Hide the dimension and annotation layers in the layers panel to see what geometry is left, and measure the main outline to confirm the units you will use for extrusion. The file is read in your browser tab and is not uploaded.

The DWG converter overview lists other targets, such as DWG to STL for 3D printing, which follows the same extrude-first approach.

Frequently asked questions