How to convert 3MF to STEP
- Drop your .3mf file into the box above, or click Choose file.
- Check the 3D preview, size and triangle count.
- Make sure STEP is selected as the output format. Adjust scale or up-axis if needed.
- Click Download. The .step file is created instantly on your device.
Why convert 3MF to STEP?
Bambu Studio, PrusaSlicer and OrcaSlicer projects are 3MF files. To modify a printed part in CAD – add a mounting hole, check a fit – convert the 3MF to STEP: every object is written as a solid, and coplanar triangles are merged into clean flat faces you can sketch on.
What changes in the conversion
- Triangles become clean faces. STEP is a CAD format, but a mesh has no parametric surfaces. Triangles on the same plane are merged into one face (with holes), curved areas stay faceted. The result is a solid you can measure, sketch on and combine – not a feature tree.
- Geometry is preserved. Every triangle, with all object transforms applied, ends up in the new file.
3MF vs STEP
| 3MF | STEP | |
|---|---|---|
| Full name | 3D Manufacturing Format | ISO 10303 (STEP AP203/AP214/AP242) |
| Stores | geometry, units, colours and (slicer-specific) print settings | exact solids, assemblies and part names |
| Colour | Yes | Yes |
| Textures | No | No |
| Units | stored in the file (usually millimetres) | stored in the file (usually millimetres) |
| Exact CAD geometry | No | Yes |
About the formats
3MF (3D Manufacturing Format) was developed by the 3MF Consortium (Microsoft, HP, Autodesk, Ultimaker and others) since 2015. It is a zipped XML package that stores meshes together with units, colours, materials and print settings. It is the modern replacement for STL in 3D printing – PrusaSlicer, Bambu Studio and Cura save projects as 3MF.
STEP (ISO 10303 (STEP AP203/AP214/AP242)) was standardised as ISO 10303 for exchanging engineering data between CAD systems. It describes exact solid geometry (B-rep surfaces, edges and assemblies) rather than triangles. It is the neutral CAD format used by SolidWorks, Fusion 360, Inventor, CATIA, FreeCAD and Onshape.
Frequently asked questions
Is this converter free?
Yes. You can convert 3MF to STEP for free – up to 5 CAD conversions a day, with no sign-up and no watermark. Pro gives you unlimited STEP conversions, batch conversion and every tool (free for 7 days).
Are my files uploaded to a server?
No. The conversion runs entirely in your browser using WebAssembly and JavaScript. Your model never leaves your computer, which also makes it safe for confidential parts and patient data.
Is there a file size limit?
There is no fixed limit. Files of a few hundred megabytes work on a typical laptop; the practical limit is your device's memory.