Free online BREP to STP converter

Source format: BREP

BREP stands for boundary representation, a 3D CAD model format that describes a solid by its faces, edges, and vertices rather than by a mesh. It is commonly used in CAD and engineering workflows, especially in systems that need precise geometric definitions for manufacturing, analysis, or model exchange. BREP files are often associated with solid modeling kernels and may be used as intermediate files when moving models between CAD applications.

Target format: STP

STP is the common file extension for STEP files, an ISO-standard format for exchanging 3D product data between CAD systems. STEP is widely supported by mechanical CAD software and is valued for its interoperability, making it a common choice for sharing precise solid models, assemblies, and product structure information across different platforms.

How to perform the conversion

The best method depends on the CAD software that created the BREP file, because BREP is often a geometry container rather than a fully standardized exchange format. If your CAD application can open the BREP file directly, export it to STEP/STP from there.

1. Open the .brep file in a CAD program that supports it, such as FreeCAD, Autodesk Fusion, SolidWorks, or the original CAD system that generated it.
2. Check that the model imports correctly and that the solid body is valid.
3. Use the export function and choose STEP or STP as the output format. In many programs this is found under File → Export or File → Save As.
4. If prompted, select a STEP flavor such as AP203, AP214, or AP242. For most modern workflows, AP242 is a strong default when available.
5. Save the file with a .stp or .step extension.

If you use FreeCAD, the process is typically: open the BREP file, verify the shape in the Part workbench, then choose File → Export and select STEP with colors or standard STEP export depending on your needs. If the file is only a raw BREP shape, you may need to import it into a document first before exporting.

Notes on quality and compatibility

Geometry fidelity is usually good when converting BREP to STEP because both formats can represent precise CAD surfaces and solids. However, there are important limitations:

• BREP files may not contain assembly structure, metadata, or colors, so that information may be lost if it was never present in the source.
• STEP export quality depends on the CAD kernel; some systems may heal or simplify geometry during export.
• Not every BREP file is interchangeable across software, because some BREP variants are application-specific.
• If the source model has invalid faces, gaps, or non-manifold edges, the STEP export may fail or produce a file that is difficult to open in other CAD tools.

For best results, use the same CAD application or kernel family that created the BREP file whenever possible, and validate the exported STEP file by reopening it in a second CAD program.