STEPSTL
STEP to STL converter
Turn a STEP file from CAD into a printable STL, with control over mesh quality.
- Nothing uploaded
- No sign-up
- Free, no limits
Drop your STEP file here
or paste it, or pick it from your device
.step · .stp
- Drop your STEP file
- Check it in 3D
- Download STL
Good to know
How to convert STEP to STL
- Drop your STEP or STP file above.
- Pick the mesh quality: Normal suits almost every print; Fine for small or precise parts; Draft for big assemblies.
- Untick any parts you don't want (fasteners, for example).
- Download one merged STL, each part as its own STL (zip), or a 3MF that keeps the parts and colours.
Mesh quality: what Draft, Normal and Fine mean
To show or print a STEP model, its curved surfaces have to be turned into triangles. This is called tessellation. Two limits control it: how far a triangle may sit from the true surface (the chord tolerance), and how sharp the angle between neighbouring triangles may get. Smaller limits mean smoother curves, more triangles and bigger files.
| Preset | Deviation (100 mm part) | Use it for |
|---|---|---|
| Draft | ≈ 0.3 mm | Big assemblies, quick looks, fast slicing |
| Normal | ≈ 0.1 mm | Most prints. Finer than a 0.4 mm nozzle can show |
| Fine | ≈ 0.03 mm | Small parts, precise holes, resin printers |
Deviation scales with the size of the model. Going finer than your printer can reproduce mostly just makes the file bigger, so Normal is the right choice for almost every FDM print.
STL or 3MF?
STL is the universal choice, but it stores only triangles: no units, no part names, no colours. If your slicer reads 3MF (Bambu Studio, PrusaSlicer, OrcaSlicer and Cura all do), the 3MF download keeps each part separate and coloured, so a multi-part assembly arrives ready to arrange or assign to filaments.
Converting in your CAD program instead
If you have the original design, you can also export a mesh directly:
- Fusion: right-click the body or component in the browser, then Save As Mesh(STL, 3MF or OBJ, with a refinement setting).
- SolidWorks: File → Save As → STL, then Options to set the resolution.
- Onshape: right-click the part, Export, choose STL and the resolution.
- FreeCAD: Meshes → Create mesh from shape, then export the mesh.
This converter is for when you only have the STEP file, don't have that software at hand, or want to print part of an assembly.
Can I convert STL back to STEP?
Only partly. STL has lost the exact surfaces, so STL to STEP gives you a solid whose flat areas are real faces but whose curves stay faceted. Recovering true holes and fillets means remodelling, so always keep the original STEP.
Just want to look at the model? Use the STEP viewer. Which slicers open STEP themselves, and how: opening a STEP file for 3D printing.
Questions
Does converting STEP to STL lose quality?
The exact curved surfaces are replaced by triangles. With the Normal setting the difference (about 0.1 mm on a 100 mm part) is finer than a 0.4 mm nozzle can print, so prints look the same. Use Fine for small, precise parts.
Which mesh quality should I choose?
Normal for almost everything. Fine for small parts, tight holes and resin printers. Draft for large assemblies where speed and file size matter more than smooth curves.
Can I export only some parts of an assembly?
Yes. Untick the parts you don't want in the list; the downloads include only the ticked parts. You can also download each part as a separate STL in one zip.
Can't my slicer open STEP files directly?
PrusaSlicer 2.5+, Bambu Studio and OrcaSlicer can, converting on import. UltiMaker Cura can't without a plugin. Converting here also lets you check sizes, pick parts and choose the mesh quality first.
Can I convert STL back to STEP?
Partly. The STL to STEP converter makes a solid with real flat faces, but curved areas stay as many small facets because STL no longer contains the exact surfaces. Keep your original STEP file.
Is there a file size limit?
No fixed limit. Everything runs on your device, so very large assemblies are limited only by your computer's memory and take longer to convert.