3dfileconverter.onlineSTL to STEP Converter: Faceted Surfaces
Convert STL to faceted STEP surface shells locally. Supports up to 20,000 triangles; exports mesh faces without reconstructing curves or parametric CAD solids.
Enable JavaScript to open a model and use the interactive workspace.
How do I use this tool?
- Choose a STL file from your device.
- Preview your model and adjust the settings.
- Create your output and download the result.
What does this tool do?
This exports triangle surface shells, not a reconstructed CAD solid. It does not restore curves, sketches or parametric features. Limited to 20,000 triangles; simplify larger meshes first.
What are the file limits?
Models are processed locally. Inputs are limited to 50 MB per file and 500,000 triangles after import. Individual operations may have lower limits described below. Performance depends on your device.
JavaScript, WebAssembly and WebGL are required for the interactive workspace.
How are models processed?
Mesh loading and rendering use Three.js. STEP import and tessellation use occt-import-js, based on Open Cascade. These sources describe the underlying libraries; this tool's supported features and limits are listed on this page.
Frequently asked questions
Does this turn STL into an editable CAD solid?
No. It writes a faceted STEP surface model in which the mesh triangles become planar faces. It does not reconstruct analytic cylinders, fillets, sketches or a parametric feature tree.
Why is the exported STEP larger than the STL?
STEP describes the points, planes, loops and faces needed to represent each triangle as a surface. This can be much more verbose than binary STL. The exporter accepts at most 20,000 triangles.
Can I export an open or non-manifold mesh?
An open mesh can be represented as an open surface shell; it does not become a closed solid. The exporter rejects degenerate triangles, non-manifold edges and inconsistent winding. Run Inspect mesh first to understand a rejection.
Which units will the STEP file use?
Set the STL source unit explicitly because STL does not carry a reliable unit. The exporter writes the selected output unit into the STEP file. Check a known dimension after opening the result in your CAD application.