Convert STP to PRT

Source format

STP and STEP are common extensions for files based on the ISO 10303 standard. These files are used to exchange 3D CAD models between systems such as SolidWorks, CATIA, Siemens NX, Autodesk Inventor, FreeCAD, and many others. STEP files usually store precise geometry, assemblies, and product structure, which makes them useful for engineering collaboration and manufacturing handoff.

Target format

PRT is a native part file format used by several CAD platforms, most notably PTC Creo and Siemens NX. However, .prt is not a universal format: a Creo .prt file is different from an NX .prt file, and other CAD systems may use the same extension for unrelated internal formats. Because of that, there is no single generic STP-to-PRT conversion standard.

How to perform the conversion

In practice, STP to PRT conversion means importing the STEP file into the CAD system that creates the desired PRT file, then saving it in that system’s native format. This is usually the best way to preserve compatibility with the target software.

Best desktop option: PTC Creo

1. Open PTC Creo.
2. Choose File → Open.
3. Select the .stp or .step file.
4. If prompted, choose the STEP import options and confirm the import.
5. Review the imported geometry.
6. Use File → Save As or File → Save a Copy to save the model as a .prt file.

Alternative desktop option: Siemens NX

1. Open Siemens NX.
2. Use File → Import → STEP or File → Open, depending on your version and workflow.
3. Select the .stp or .step file.
4. Check the imported body for geometry issues and repair them if needed.
5. Save the model as an NX native .prt file with File → Save As.

Free option: FreeCAD

1. Open FreeCAD.
2. Use File → Open to load the STEP file.
3. Inspect the imported solid or shape.
4. Save the project in FreeCAD’s native format if needed.

Important: FreeCAD can open STEP files, but it does not create a true Creo or NX .prt file. If you need a valid .prt for Creo or NX, you must use that CAD system or a compatible converter that supports the target native format.

Online converters

Online converters are usually not suitable for STP to PRT because .prt is proprietary and depends on the target CAD platform. Reputable online CAD services such as CAD Exchanger, Autodesk Viewer, or Onshape can help you view, translate, or move STEP data into other workflows, but they typically do not generate a valid native Creo or NX .prt file.

Quality and compatibility notes

• Feature history is usually lost when converting from STEP to PRT, because STEP mainly stores geometry and assembly data, not the original parametric design tree.
• The imported result is often a featureless body or imported part, unless the CAD system can recognize and rebuild features.
• Assembly structure, colors, layers, and metadata may import only partially, depending on the source file and import settings.
• PRT is not interchangeable across CAD systems; a Creo .prt file cannot be used as an NX .prt file, and vice versa.
• For the best result, use the same CAD platform that will later edit, validate, or manufacture the part.

Bottom line

If you need to convert STP to PRT, the practical method is to open the STEP file in Creo or NX and save it as that program’s native .prt file. There is no universal one-click converter for all PRT variants, and online tools usually cannot create a true native PRT file.