The world of CAD file formats can be confusing, with dozens of proprietary and universal formats to choose from. Choosing the wrong format can result in lost data, manufacturing errors, or wasted time. Here's a practical guide to the formats that matter.
STEP (.stp, .step) is the gold standard for exchanging CAD data between different software. It preserves solid geometry, surfaces, assemblies, and even some metadata. Use STEP when sharing files with manufacturers, partners, or anyone using different CAD software.
IGES (.igs, .iges) is an older universal format that handles surfaces and wireframes well but is less reliable for solid bodies and assemblies. It's still widely used in aerospace and automotive industries for legacy compatibility. Use IGES as a fallback when STEP doesn't work.
STL (.stl) represents 3D objects as triangle meshes. It contains no material, color, or scale information — just geometry. STL is the standard format for 3D printing (FDM, SLA, SLS). Use STL for additive manufacturing, but never for precision machining.
3MF (.3mf) is the modern replacement for STL in 3D printing. It includes color, material properties, and build information. If your 3D printer or service bureau supports 3MF, prefer it over STL for richer print data.
Parasolid (.x_t, .x_b) is used by SolidWorks, NX, and Solid Edge. It's an excellent exchange format within the Siemens ecosystem and preserves solid geometry accurately. Many manufacturers prefer Parasolid alongside STEP.
Native formats (SLDPRT, F3D, IPT, etc.) preserve the full design intent including parametric features, design history, and constraints. Share native files when collaborating within the same CAD platform. Never rely solely on native files for cross-platform exchange.
DXF/DWG are 2D drawing formats from AutoCAD. Use DXF for sharing 2D technical drawings, laser cutting profiles, and CNC router paths. DWG is AutoCAD's native format; DXF is the universal exchange version.
USDZ and GLB are 3D formats optimized for AR and web. USDZ (Apple) and GLB (Google/web) are what you need for augmented reality experiences and web-based 3D viewers. These are display formats — not manufacturing formats.