Free online OBJ to IGES converter

A legacy CAD, CAM, inspection, or manufacturing program may accept IGES but not OBJ, requiring the mesh to be converted before it can be opened or shared. Direct conversion usually produces faceted IGES geometry; smooth, editable CAD surfaces require reverse engineering.

What the OBJ format is

OBJ is a text-based polygon-mesh format used for 3D scans, visualization models, game assets, and mesh exchange. It stores vertex coordinates and polygon faces, and may also store texture coordinates, vertex normals, and material references in a separate .mtl file.

Blender, MeshLab, FreeCAD, Fusion, Rhino, 3D scanners, and many modeling or rendering applications can import or export OBJ. The format commonly comes from scans, triangulated models, and graphics workflows rather than parametric CAD systems.

What the IGES format is

IGES, identified by .igs or .iges, is a neutral CAD exchange format used by CAD, CAM, CAE, inspection, and manufacturing software. Its entities can represent lines, arcs, points, wireframes, NURBS curves, trimmed surfaces, and, in some implementations, boundary-representation solids.

IGES represents engineering geometry rather than polygon rendering data, but it does not contain the feature history or parametric design tree of the originating CAD model. Converting a mesh does not automatically create clean NURBS surfaces, design features, or a watertight solid.

How to convert OBJ to IGES

Direct conversion in FreeCAD

1. Open FreeCAD and import the .obj file through File → Import. Use the source unit or set the correct scale if the import dialog provides that option.
2. Switch to the Part workbench and select the imported mesh in the model tree.
3. Choose Part → Create shape from mesh. Set a tolerance appropriate to the model's size and create the shape.
4. Select the resulting shape and choose File → Export. Save it with the .igs or .iges extension.
5. Open the exported file in the target CAD system and check its scale, face count, gaps, and face orientation.

This method turns mesh triangles into individual planar CAD faces. It can provide reference or inspection geometry, but a dense OBJ may produce thousands or millions of IGES faces that are slow to load and difficult to edit.

Rebuilding usable CAD surfaces

For an editable engineering model, first repair the mesh and remove unnecessary polygons in a mesh or reverse-engineering application. Then fit curves and NURBS surfaces to the important regions, trim and join those surfaces, check continuity, and export the rebuilt geometry through File → Export → IGES. Rhino and dedicated reverse-engineering systems support this workflow, but the result requires manual modeling and depends on scan quality and surface complexity.

For a conversion without installing software, upload the file to 101convert.com, convert it for free, and download the IGES result. Verify the output in a CAD viewer before using it for dimensional design, tooling, or machining.

Quality and compatibility limits

• OBJ does not reliably define measurement units. Confirm the source unit and apply the required scale during import or in the target CAD system.
• Textures, image maps, materials, and most color or rendering information do not transfer to IGES, which primarily carries geometric entities.
• Duplicate vertices, holes, non-manifold edges, self-intersections, flipped normals, and disconnected parts can prevent mesh-to-shape conversion or create invalid faces. Repair the OBJ before exporting.
• Direct conversion preserves the faceted nature of the source mesh. It cannot recover smooth surfaces or design intent that the OBJ never contained.
• IGES files are commonly exchanged as collections of curves and surfaces rather than guaranteed watertight solids. If the recipient needs a solid CAD model, heal and close the surfaces or remodel the part; after that work, STEP is often a more suitable solid-exchange format.
• Different IGES importers handle entity types, tolerances, surface trims, and colors differently. Reopen the exported file in the exact software that will use it.