Drop your .stl file (ASCII or binary) on the converter, select the unit the model was made in, and press Convert to STEP. You get a solid STEP file (AP214) for CNC machining, CAD, or CAM. This mesh to STEP conversion needs no account.

Yes, when the mesh is watertight or becomes watertight after automatic repair. CAD and CAM software can measure, section, and toolpath it. Holes, slots, and fillets that match a cylinder exactly are true cylindrical faces, so CAM can select them as holes. Other curved areas stay as flat facets, so remodel tight-tolerance features in CAD.

A solid needs a closed mesh where every edge is shared by exactly two triangles. If the mesh check still shows open edges, close the gap in a mesh tool such as Blender or Meshmixer and convert again. A surface model will not upload to the Xometry Instant Quoting Engine®, which needs a solid. Files with over 12,000 faces or 15 MB can also be rejected. In that case, ask for the native CAD file.

The converter rebuilds a cylinder or cone only when the triangles lie on it exactly and every edge can be written as an exact circle or line. Spheres, tori, freeform blends, chamfered holes away from the main axis, and holes that meet a fillet stay flat, because a partial curve would stop CAD from building a solid. Turn off Recognize cylinders to keep flat facets everywhere.

Automatic: welding coincident vertices, removing degenerate triangles, splitting non-manifold vertices, and capping small flat gaps. Not automatic: filling large or curved holes or fixing self-intersections, which would mean inventing geometry. The mesh check lists what was repaired and what remains.

STL files have no body tags, so the tool finds each disconnected shell in the welded mesh, checks it for watertightness, and writes it as a separate STEP solid. This covers several parts on one print bed.

Yes, when the binary STL stores 16-bit RGB color in the 2-byte attribute of each facet (VisCAM and Magics format). These colors are written as STEP face colors. ASCII STL has no color.

Up to 300,000 triangles convert directly. Up to 1,200,000 triangles are simplified to 300,000 first, which can reduce the number of recognized cylinders, and a notice appears. Above 1,200,000, decimate the mesh in your modeling tool first.

The STEP file is always in millimeters, so SolidWorks, Fusion 360, Creo, NX, and other CAD systems open it at the correct size. STL files have no units, so you select what the numbers in your file mean. Example: 88 with cm selected becomes 880 mm. If the bounding box looks 10 or 1000 times off, change the unit.

STEP stores every face, edge, and vertex as a separate text record, so a triangulated STEP file is typically 5 to 15 times larger than the STL. Merging flat triangles and rebuilding cylinders reduces this.

It is free, and your file is never uploaded. Everything runs in a background thread in your browser tab, so confidential designs stay on your computer.