STL → DXF · Section & outline
STL to DXF
Cut a horizontal section through an STL and export it as a DXF outline for laser cutting or CNC — or hand the whole mesh over as DXF 3DFACE triangles. Free, instant, 100% local.
DXF is a 2D drawing format, so a 3D model can't go across unchanged. You get a real section through the part — or every triangle as 3DFACE entities if you need the full shape in CAD.
Converting an STL to DXF
STL is a 3D triangle mesh; DXF is a 2D drawing format. There's no conversion that keeps everything, so this tool gives you the two that are actually useful — and tells you which one you're getting.
A 2D section cuts the model with a horizontal plane at a height you choose and exports the outline of that cut as closed DXF polylines. This is what you want for laser cutting, waterjet, plasma or CNC profiling, and for dropping a real footprint into a 2D drawing.
3D faces writes every triangle straight through as a DXF 3DFACE entity. The shape is unchanged, so a CAD package that imports faceted geometry gets the whole model — but the file is large and it's still a mesh, not a solid with feature history.
Because it's a genuine section and not a flattened silhouette, curved or tapered walls give a different outline at different heights. Pick the height that matters for your cut — the slider updates the preview live.
Frequently asked questions
- How do I convert an STL to DXF?
- Drop the STL above, leave the mode on 2D section, and drag the cut-height slider until the preview shows the outline you need. Then click Download DXF. Nothing is uploaded.
- Is this STL to DXF converter free?
- Yes — free, no signup, no watermark, no file-size paywall.
- Why does an STL have to become a section instead of the whole shape?
- DXF's 2D entities can only hold flat geometry. A mesh has depth, so something must be chosen: a cut at one height, or the triangles themselves as 3DFACE entities. Anything else would be throwing away information without saying so.
- Which mode should I pick?
- Cutting a flat part on a laser or router: use 2D section. Getting the 3D shape into a CAD package that accepts faceted geometry: use 3D faces. If you just want to view or print the model, you don't need DXF at all.
- The outline has amber gaps — what does that mean?
- Those chains didn't close, which means the mesh has holes or non-manifold edges where the plane crossed it. They're exported as open polylines rather than dropped. Run the model through STL Repair first if you need a closed cut path.
- Can I convert other formats to DXF here?
- Yes. The dropzone accepts OBJ, GLB, 3MF, PLY, STEP, IGES, FBX and DAE as well as STL — anything Flip3D can read gets sectioned the same way.
- What DXF version does it write?
- AutoCAD R12 (AC1009) ASCII with millimetre units. Sections use POLYLINE entities; the 3D mode uses 3DFACE.
- Does my STL get uploaded to a server?
- No. There is no server and no upload. The mesh is read and sectioned entirely on your device.