Convert STEP to 3MF
Convert a STEP file to 3MF in your browser. Free, no upload, no sign-up.
Convert STEP files to 3MF directly in your browser. The converter reads the exact STEP geometry with the OpenCascade CAD kernel running in WebAssembly, tessellates it at the quality you choose and writes a 3MF file. Nothing is uploaded, there is no file size limit beyond your computer's memory, and the result downloads instantly. 3MF records the unit and can hold several objects with colors, so the model opens in the slicer at the right size without guessing.
How to convert STEP to 3MF
- 1Drop your STEP file
Drag a .step file onto the box above or click to choose one. The exact geometry is tessellated into triangles in your browser using OpenCascade (the same kernel FreeCAD uses). You can control the mesh density before exporting. Large assemblies may take a while; the first load downloads a 7 MB engine.
- 2Pick the mesh quality
Fine gives smoother curves and a larger file, coarse keeps large assemblies light. The default suits most 3D printing jobs.
- 3Check the preview
The model renders in 3D so you can confirm it loaded correctly. Dimensions, volume and triangle count are shown next to it; open edges are flagged if the mesh is not watertight.
- 4Download the 3MF
Adjust the export options if needed and click download. The exported file declares millimeters as its unit and contains the mesh as a single object.
What is a STEP file?
STEP (ISO 10303, files ending in .step or .stp) is the neutral CAD exchange format. Unlike mesh formats it stores exact B-rep geometry: analytic surfaces, NURBS, edges and assembly structure with real units. Every CAD system can export STEP, and it is what you receive from suppliers, McMaster-Carr or GrabCAD.
Commonly used by: SolidWorks, Fusion 360, Onshape, FreeCAD, CATIA, Siemens NX, machine shops
The exact geometry is tessellated into triangles in your browser using OpenCascade (the same kernel FreeCAD uses). You can control the mesh density before exporting. Large assemblies may take a while; the first load downloads a 7 MB engine.
What is a 3MF file?
3MF is the modern replacement for STL, published by the 3MF Consortium (Microsoft, Autodesk, HP, Prusa and others). It is a ZIP archive containing XML that stores units, colors, materials, multiple objects and print settings. Slicers such as Bambu Studio and PrusaSlicer use it as their project format.
Commonly used by: Bambu Studio, PrusaSlicer, Cura, Windows 3D Builder, Fusion 360
3MF records the unit and can hold several objects with colors, so the model opens in the slicer at the right size without guessing.
STEP vs 3MF
| STEP | 3MF | |
|---|---|---|
| Full name | Standard for the Exchange of Product Data (ISO 10303) | 3D Manufacturing Format |
| Encoding | Text | ZIP container |
| Geometry type | Exact (B-rep / curves) | Triangle mesh |
| Colors | Yes | Yes |
| Textures | No | Yes |
| Materials | No | Yes |
| Stores units | Yes | Yes |
| Multiple objects | Yes | Yes |
| Typical use | SolidWorks, Fusion 360, Onshape | Bambu Studio, PrusaSlicer, Cura |