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3DAI
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Convert STEP to STL in Your Browser

STEP (.step or .stp) is how CAD programs such as SolidWorks, Fusion, Onshape, FreeCAD and Inventor exchange exact solid models. A slicer needs a triangle mesh instead. This page runs the open-source Open CASCADE kernel in your browser to tessellate the solids into a printable STL, so the file is not uploaded and you choose how fine the mesh is.

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How to use it

  1. 1

    Add your STEP file

    Drop a .step or .stp on the box or click to pick it. The CAD kernel (about 3 MB) downloads the first time you use the page.

  2. 2

    Choose the quality

    Standard suits most prints. Use Fine or Very fine for small curved parts; Draft keeps the file small for big flat parts.

  3. 3

    Check the preview

    The grey model is the mesh that goes into the STL. The panel shows triangles, size in the chosen unit and the number of parts.

  4. 4

    Download the STL

    Save one binary STL with every part, or one STL per part in a ZIP.

What to know before you convert

  • STEP AP203, AP214 and AP242 solid and surface geometry is supported. Sketches, drawings, PMI annotations and assembly constraints are ignored.
  • STL stores only triangles, so colours, part names and the exact curved surfaces are lost. Curves become flat facets; the quality setting controls how fine they are.
  • Files are converted to millimetres by default, using the unit stored in the STEP file. Pick another unit only if your slicer expects one.
  • The CAD kernel needs a lot of memory. Files up to 50 MB are accepted, and a conversion that would produce more than 4 million triangles is stopped with a message to use a coarser quality.
  • IGES, Parasolid (.x_t), SolidWorks and native CAD files are not supported. Export STEP from your CAD program first.

Don't have a model?

Generate one from a sketch, image or text. Our AI generators give you a 3D model with an STL download for printing. They use credits; this converter does not.

Sketch to STL →Draw it, get a printable model.Image to STL →One photo of an object.Text to STL →Describe it in a sentence.

Frequently Asked Questions

Drop the file above. The page loads the Open CASCADE geometry kernel as WebAssembly, reads the solids and turns their faces into triangles, all in your browser tab. When it finishes you download a binary STL.
Quality sets how far a flat facet may stray from the true curved surface, as a share of the part size. Standard is fine for most prints. If round holes or fillets look faceted in the slicer, convert again with Fine or Very fine. Finer settings make the STL larger and slower to slice.
Yes. .step and .stp are two extensions for the same ISO 10303 format, and both open here.
STEP files carry a unit, and the converter writes the STL in millimetres, which is what slicers expect. If you picked another output unit, the slicer will read those numbers as millimetres. A model that was drawn at the wrong scale in CAD stays that way.
Yes. Assemblies keep their part positions. Download everything as one STL, or choose the ZIP option to get one STL per part.
No. The STEP file is read and converted inside your browser with the open-source Open CASCADE kernel compiled to WebAssembly. Nothing is sent to our servers, there is no account, and no credits are used.