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 CAD, re-modeling, and CNC machining quotes. If you try it, verify all critical dimensions in your CAD system first. Xometry assumes no liability for results from production use of converted files. This mesh to STEP conversion runs in your browser.

CAD software can measure and section it, and quoting systems can read it. Holes, slots, and fillets that match a cylinder exactly are true cylindrical faces. Other curved areas stay as flat facets. Treat the file as a reference model and check dimensions in CAD before any production use.

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.

Yes. Any CAD program that reads STEP can open it. Because it comes from a mesh, curved areas that are not cylinders stay as flat faces, so remodel them if you need to edit them.

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.