STEP to STL Converter

Convert CAD solids (STEP/STP) into clean, watertight STL meshes ready for your slicer — tessellated by a real CAD kernel at 0.05 mm tolerance.

Real CAD kernelWatertight outputSlicer-readyFree ≤25 MB

From exact surfaces to printable triangles

STEP files describe exact analytic surfaces; printers need triangles. The quality question is tessellation tolerance: too coarse and cylinders print faceted, too fine and files explode. StlWiz tessellates with OpenCascade at 0.05 mm chordal tolerance — visually smooth on FDM and resin prints without bloated files — then verifies the mesh is closed and correctly oriented.

Frequently asked questions

How do I convert a STEP file to STL?
Upload the .step or .stp file above and download the STL. The mesh is generated at 0.05 mm tolerance, merged and normal-checked — ready for PrusaSlicer, Cura, Bambu Studio or any slicer.
Is the output watertight?
Yes for valid solids — we merge vertices and fix normals after tessellation. If your STEP contains open shells, the STL mirrors that geometry; run it through our STL repair tool if your slicer complains.
Is this converter free?
Yes — up to 10 conversions a day and files up to 25 MB, no account needed. Larger files (up to 60 MB) and high-detail STEP output use credits ($9 for 20). Everything runs server-side on real geometry kernels, and failed jobs auto-refund.
What happens to my files?
Files are uploaded only to run your conversion and stored briefly so you can download the result. We don't share them, mine them or train on them. See our privacy policy.