Convert IGES to STL

Why people convert IGES to STL

An old surface file that you want to look at, measure or print.

The IGES surfaces are evaluated and tessellated into triangles, and the unit comes from the file's own Global section, so the size is right.

The thing to check is whether the mesh came out closed. IGES was designed around surfaces, and solids were added later through an entity that not every exporter writes. A great many IGES files in circulation are collections of surfaces that look like a solid but are not stitched into one, with small gaps between neighbouring patches. Those gaps are real, and they become holes in the mesh.

This site reports whether the result is watertight and how many open edges it has. If it is not closed, a slicer cannot decide what is inside it, and you have two options: heal the surfaces first in a CAD package with a sew or stitch command, or repair the mesh afterwards in MeshLab or your slicer's own repair tool. Healing upstream gives the better result.

What you get

You get a binary STL file containing triangles. The reader tessellates supported surfaces or uses saved render meshes where required by the source format. Inspect curved faces at the intended output size. The triangle count depends on the model and the reader's meshing settings.

Not carried across by this conversion: a recorded unit, colour.

The conversion runs in your browser. Your file stays on your computer and is not uploaded.

What to check afterwards

• IGES declares its unit in the file. Check the output dimensions in the receiving application, especially when its import settings can override the unit.
• Colour is lost. STL has nowhere to store it. If colour matters, pick a target that keeps it: 3MF, GLB, PLY or USDZ.
• Curves become facets. IGES stores exact surfaces, so a hole is a cylinder with a radius. STL stores triangles, so that cylinder becomes a many-sided prism. Look at curved faces in the result at the size you intend to make the part.
• Coordinates are stored as 32-bit floats. For a part measured in millimetres that's far finer than any machine tolerance. For a model spanning hundreds of thousands of units it isn't.

If you need something this conversion cannot give you

If the unit has to be unambiguous, convert to 3MF instead. It records the unit in the file, so nobody downstream has to assume millimetres and nobody has to scale by 25.4 after the fact.

If colour has to survive, convert to 3MF for printing, GLB for the web, or PLY if the colour is per-vertex scan data.

If you need editable CAD geometry, don't convert at all. Open the IGES file directly in FreeCAD, Fusion, Onshape or SolidWorks. Every mesh format destroys the exact surfaces, and no later conversion brings them back.

If your slicer accepts 3MF, consider it when you need a unit declaration or separate components in the output. Keep the original project for its print settings.

Going the other way

This site reads IGES but does not write it. For the reverse conversion, use an application that can export IGES.

How we know this conversion works

This pair was checked against 1 file from the test corpus on 2026-09-04. Each run parses its own output back in and compares the bounding box, the triangle count and, for closed solids, the volume against the input.

A pair that fails those checks doesn't get a page. That's why this site lists 120 conversions and not the several hundred a format-times-format grid would suggest.