Convert SLDPRT to STP

A supplier, CAD system, CAM package, or inspection device may accept STEP but not the native SolidWorks part format. Converting the file provides interoperable geometry while keeping the original .sldprt as the editable source.

What the SLDPRT format is

.sldprt is SolidWorks' proprietary part-file format. It can contain a single part with sketches, dimensions, feature history, configurations, appearances, materials, custom properties, and, in some cases, multiple solid bodies. Engineers, manufacturers, suppliers, and product-development teams use it in SolidWorks workflows.

Non-SolidWorks software may require a licensed translator or an importer to open SLDPRT files. A file may also depend on referenced design data, configurations, or SolidWorks features that another application cannot interpret.

What the STP format is

.stp and .step are extensions for ISO 10303 STEP files, a neutral CAD-exchange format supported by SolidWorks, Autodesk Inventor, Fusion, CATIA, Siemens NX, FreeCAD, Onshape, CAM systems, and inspection software.

STEP normally transfers boundary-representation geometry as a solid or surface model. It does not preserve the SolidWorks feature tree, sketches, mates, equations, or parametric edit history; the recipient usually gets an imported, non-parametric solid. STEP is useful for cross-platform exchange because it avoids requiring the recipient to own SolidWorks and generally retains precise geometric surfaces rather than a mesh.

AP203, AP214, and AP242 are STEP application protocols. AP214 and AP242 can carry more product, color, layer, assembly, and metadata information than older AP203 workflows, but support varies by exporter and receiving application. Confirm the required protocol before exporting.

How to convert an SLDPRT file to STEP

Using SolidWorks

1. Open the .sldprt file and rebuild the model. Resolve rebuild errors and activate the configuration that must be delivered.
2. Choose File → Save As.
3. Set the file type to STEP. Depending on the SolidWorks version and license, available choices may include STEP AP203, STEP AP214, or STEP AP242. Select the protocol supported by the recipient; AP214 is often a compatibility choice, while AP242 is appropriate when both systems support it.
4. Open Options if available. Set the output coordinate system, units, and other STEP options required by the receiving system. Do not change units without confirming the intended result.
5. Save the file with a .stp or .step extension.
6. Reopen the exported file in SolidWorks or the recipient's CAD viewer. Check that it is a valid solid, has the expected orientation and dimensions, and contains every required body.

For a multibody part, inspect the export setting that controls whether bodies become one STEP file or separate files. Use one file when the recipient needs the complete multibody model; use separate files when bodies are manufactured, quoted, or processed independently.

Using other desktop or cloud software

CAD Exchanger provides desktop and web conversion workflows that can translate SLDPRT to STEP without SolidWorks. Import the file, choose STEP as the export format, select the required protocol or units when offered, export, and validate the result in a CAD viewer. Its ability to read a particular SLDPRT version depends on the translator version and the source file's contents.

Onshape can import SLDPRT into a document and export the resulting part or assembly as STEP. Upload the file, open the imported tab, use the tab's export command, choose STEP, and download the result. Check the privacy and data-retention terms of the Onshape plan before uploading proprietary designs.

FreeCAD is suitable for STEP export, but direct SLDPRT import is not a dependable standard capability across FreeCAD installations. Use it only when the installed importer successfully opens the file as exact solid geometry; otherwise export from SolidWorks or use a translator with explicit SLDPRT support.

Quality and compatibility limits

• STEP cannot recreate the original SolidWorks feature tree. Keep the source .sldprt as the authoritative editable file.
• Suppressed features, inactive configurations, display states, drawings, decals, simulation data, equations, and some custom properties may not transfer. Activate and verify the required configuration before export.
• Check units, scale, coordinate orientation, body count, colors, names, missing faces, gaps, sliver surfaces, and solid validity after import. A file that opens successfully may still be unsuitable for machining or inspection.
• For manufacturing, run the receiving system's geometry or healing checks and compare critical dimensions against the original. Re-export if the recipient reports invalid topology or missing faces.
• Online conversion is inappropriate for confidential, export-controlled, or contract-restricted designs unless the provider's storage, deletion, security, and data-processing terms allow the upload.