Convert FreeCAD (FCStd) to STL for 3D Printing
Upload a FreeCAD .FCStd document and get one binary STL of the solids that make up the model, meshed by FreeCAD 1.1 in millimeters. Sketches, datum planes and the hidden inputs of boolean operations are left out, so the print matches the finished part.
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Why Convert FCStd to STL, and How It Works
An .FCStd file is a ZIP archive holding a FreeCAD document: the parametric feature tree, sketches with their constraints, and a cached B-rep shape for each feature. No slicer understands that. Normally you would open FreeCAD, select the right body and use File > Export with mesh settings you hope are right.
On our server, FreeCAD 1.1 opens the document and works out which objects form the model. It skips origin planes, axes and datums, treats a PartDesign Body as one solid (its Tip feature), drops anything another exported object consumes, such as the box and cylinder inside a Cut, and ignores flat sketches when solids are present. When the file records which objects were visible, only those are exported. The kept solids are then meshed within 0.1 mm of their exact surfaces.
Fillets, chamfers, patterns and booleans come through because they are already part of the solid FreeCAD saved. The feature tree, constraints, colors and object names do not; STL has no place for them. All selected objects go into one STL at their document positions, as separate shells rather than one fused solid. A document that contains only meshes, such as an STL you imported into the Mesh workbench, is exported as those meshes; in a document that also has solids, the meshes are left out.
Some files arrive without their cached shapes, for example when a script or another program wrote them. The converter then recomputes the document so the parts are rebuilt from their parameters, and if FreeCAD still finds nothing, it reads the stored shape files straight out of the archive as a last resort.
This page serves people who received a FreeCAD file and want to print it, and FreeCAD users who slice on a different computer, the searches behind "save FreeCAD as STL" and "how to open an FCStd file for 3D printing".
How to Convert FCStd to STL
- In FreeCAD, hide anything you do not want printed (reference parts, an alternative version, a fixture), recompute and save.
- If the model is an assembly whose parts are linked from other .FCStd files, export it to STEP from FreeCAD instead, because a single upload cannot carry the linked files.
- Drop the .FCStd file on this page; STL is already chosen. Up to 10 files can go in one batch without a paid plan.
- Click Convert. FreeCAD documents usually finish in about a second.
- Download the STL and load it in Cura, PrusaSlicer, Bambu Studio or another slicer. If several bodies came through, split them into separate objects in the slicer to arrange them.
Key Conversion Features
- Runs FreeCAD 1.1, so documents saved in FreeCAD 1.0 and 1.1 open, not only older 0.x files
- Exports the finished model: Body tips, boolean results, Part primitives and arrays
- Leaves out datum planes, origin axes, consumed boolean inputs and 2D sketches
- Rebuilds documents saved without cached shapes by recomputing them
- Names missing linked part files instead of exporting an incomplete assembly
- Fixed 0.1 mm surface deviation, output as binary STL in millimeters
Video Tutorial
Detailed guide on how to convert FCSTD files to STL quickly, for free, and without losing original quality. Perfect if you need to process file formats, reduce size, or upload files to systems that on
Frequently Asked Questions
Can I convert FCStd to STL without installing FreeCAD?
Upload it here. FreeCAD runs on our server and writes the STL, so all you need is a browser. Files up to 50 MB work for free without an account.
Why did I get a "no geometry" error?
It is the most frequent failure on this page. The document has no solids or surfaces to mesh: typically it holds only sketches or 2D Draft objects, or it is empty. Pad or extrude the sketch into a solid in FreeCAD and save again. If a 2D profile is what you need, convert the file to DXF, which keeps sketches as curves.
The error says parts are linked from other files. What now?
Your document is an assembly built from App::Link objects, as the FreeCAD 1.x Assembly workbench and Assembly4 do, and its parts live in separate .FCStd files. The converter names the missing files and stops rather than print half the model. Open the assembly in FreeCAD, export everything to STEP, and convert that STEP to STL.
What do "Invalid project file" or "Error reading compression file" mean?
The upload is not a complete FCStd archive. An FCStd is a ZIP file, and one cut short while saving, syncing or downloading cannot be opened. Save it again from FreeCAD; if FreeCAD crashed, the .FCBak backup next to the file can be renamed to .FCStd and uploaded.
Which FreeCAD versions are supported?
The converter runs FreeCAD 1.1, which opens documents from the 1.x series as well as older 0.x releases. A file from a newer development build may use features 1.1 does not know about.
Is the mesh fine enough to print?
Curved surfaces are approximated within 0.1 mm, and each facet covers at most roughly 0.5 radians of arc. That is adequate for FDM and most resin prints. For very small, smooth parts, mesh them in FreeCAD's Mesh Design workbench with a lower surface deviation.
Can I convert STL back to FCStd?
Not here; FCStd is not an output format. FreeCAD itself can import an STL and turn it into a solid with Part > Create shape from mesh, though the result stays faceted and has no parametric history.
Do you keep my FreeCAD files?
No. The document is processed on our servers and deleted once the STL has been written; the STL itself is purged automatically about four hours later.