Free online 3MF to IGES converter

What the 3MF format is

3MF, or 3D Manufacturing Format, is a ZIP-based format designed for additive manufacturing. A 3MF package can contain a triangle mesh, object and build information, colors, materials, textures, print settings, and metadata in a single file.

Microsoft developed the format through the 3MF Consortium. Programs such as Microsoft 3D Builder, Autodesk 3D printing tools, Ultimaker Cura, PrusaSlicer, Bambu Studio, and other slicers can create or export 3MF files. You commonly encounter it after downloading a printable model or exporting a design for a 3D printer.

What the IGES format is

IGES, usually stored with the .igs or .iges extension, is an exchange format for CAD geometry. It can store curves, wireframes, surfaces, dimensions, annotations, and some solid-model representations.

Engineering applications use IGES for exchanging geometry between older and newer CAD systems, CNC preparation, inspection, tooling, and technical documentation. Its broad software support is an advantage, but IGES is less structured than newer formats such as STEP and may not preserve a model's native feature history, constraints, or parametric operations.

How to convert 3MF to IGES

Using the online converter

You can convert the file on 101convert.com for free without installing software:

1. Open the 3MF-to-IGES converter on the website.
2. Select the source file with the .3mf extension.
3. Start the conversion and wait for processing to finish.
4. Download the resulting .igs or .iges file.
5. Open the output in the destination CAD application and verify its scale, orientation, surface closure, and critical dimensions.

Using FreeCAD

FreeCAD can provide a local workflow for mesh-based 3MF files:

1. Open FreeCAD and choose File → Open, then select the .3mf file. The model normally loads in the Mesh workbench.
2. Switch to the Part workbench.
3. Select the imported mesh in the model tree and choose Part → Create shape from mesh. Set a tolerance appropriate to the model; a smaller tolerance follows the triangles more closely but can create a very large shape.
4. Select the resulting Part shape and choose File → Export.
5. Set the output type to IGES and save it as model.igs.
6. Reopen the exported file in FreeCAD or another CAD program and inspect the result.

Quality and compatibility limitations

A 3MF file normally contains a triangle mesh, while IGES is primarily intended for CAD curves and surfaces. Converting the file does not recreate the original editable CAD features. A mesh-to-IGES workflow usually turns every triangle into a planar face or attempts a surface approximation, producing a faceted or very large IGES file.

For accurate engineering edits, use the original parametric CAD file or a reverse-engineering tool that fits NURBS surfaces to the mesh. Check the converted model for gaps, inverted normals, duplicate faces, non-manifold edges, and missing color or material data; these 3MF properties often have no direct IGES equivalent.

Confirm units before export and import. 3MF commonly uses millimeters, while IGES records a unit designation that some older programs interpret inconsistently. Measure a known feature after conversion instead of relying only on the displayed scale. Highly detailed meshes may exceed the face or entity limits of the receiving CAD system, so simplify or decimate the mesh before conversion when the source contains more triangles than the required manufacturing accuracy justifies.