Free STEP to STL converter
Convert STEP to STL for 3D printing.
Slicers like Cura, PrusaSlicer and Bambu Studio want STL. Drop a STEP or STP file and Caddis tessellates it into a binary STL in your browser. Your design never leaves your computer.
Why convert STEP to STL?
STEP is the neutral format engineers exchange between CAD systems, and suppliers often send parts that way. 3D printers and many mesh tools need a triangle mesh instead, and that's what STL is.
How to convert STEP to STL
- Choose your STEP or STP file above, or drag it onto the box.
- Check that STL is selected. You can switch to any other output.
- Select Convert. The file downloads straight away. Nothing is uploaded.
Good to know
- STL has no units. STEP files are usually in millimetres, which is what slicers assume.
- Assemblies are combined into one mesh. Convert to OBJ to keep the parts as separate groups.
- Caddis reads tessellated and common analytic B-rep STEP geometry and reports any surface type it can't read rather than guessing.
What converts, and what doesn't
- Every output is a triangle mesh. STEP and IFC solids are tessellated for display, so the result is not an editable solid or B-rep.
- When the source names its parts (STEP and IFC assemblies, for example), they become named groups in OBJ. STL, PLY and GLB hold a single combined mesh.
- Colours and materials are not carried over.
- Coordinates keep the source units, except GLB, which is scaled to metres when the source declares its units.
Frequently asked questions
STEP or STP — is there a difference?
No. .step and .stp are the same ISO 10303-21 format with different file extensions. Both convert the same way.
How smooth will curved surfaces be?
Curved faces are tessellated at the resolution Caddis uses for display, which prints smoothly at typical part sizes. For very large or very precise parts, export from your CAD system with a finer mesh setting.
Is my file uploaded?
No. The file is read and converted by the Caddis engine running inside your browser tab. It is never sent to a server, so confidential drawings stay on your device.
Is it really free?
Yes. There's no account, watermark, page limit or daily quota. The converter runs on your own computer, so it costs us nothing per file.
Need to measure or mark up the drawing too?
The same engine powers the free Caddis viewer on the web and on iPhone. Open DWG, DXF, STEP and STL files, measure, and add markup, all on your device.
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Universal CAD converterDWG version checkerDWG to DXFDWG to PDFDWG to SVGDWG to PNGDXF to PDFDXF to SVGDXF to PNGDXF to R12 DXFSTEP to OBJSTEP to GLBSTL to OBJOBJ to STLSTL to GLBPLY to STLIFC to OBJIFC to GLBSLDPRT to STL