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.
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.
If your CAD package handed you a .stp file rather than a .step, nothing is different — both are ISO 10303 STEP files, and the three-letter extension is a leftover from DOS-era filename limits. SolidWorks and Siemens NX tend to write .stp; FreeCAD, Fusion 360 and CATIA usually write .step. This converter reads either, and you do not need to rename anything before uploading.
Same for how people say it: STP to STL, STEP file to STL, convert step to stl online — one conversion, one page. Going the other way, from a printable mesh back to a CAD solid, is a genuinely harder problem and lives on our STL to STEP converter.
Every converter runs the same geometry engine — see all 20 conversions.