Initial Graphics Exchange Specification .iges
The CAD exchange standard STEP replaced. Still everywhere.
What an .iges file holds
IGES was the first widely adopted neutral CAD format, standardised in 1980, and it carried surfaces and curves between systems for two decades before STEP displaced it. It has been frozen since 1996 and never quite died, because so much archived tooling, mould and aerospace geometry exists in nothing else. IGES describes surfaces rather than closed solids, so imported models are likelier to arrive with gaps.
Commonly seen in: legacy CAD archives, CATIA, Siemens NX, mould and tooling, aerospace.
| Data | Stored in IGES |
|---|---|
| Geometry | Yes |
| Materials and colour | Yes |
| Texture maps | No |
| Animation and rigs | No |
| Scene hierarchy | Yes |
| Read here | Yes |
| Written here | No |
Tested against a real file
The last sweep loaded Cube 10x10.igs from occt-import-js test files with its 1 sidecar files through the viewer on this site: 12 triangles across 1 meshes and 1 materials, in 2.8 seconds. Every format's result is on the test results page, run 2026-09-08.
Which way is up
IGES is a Z-up format, which most of the rest of 3D is not. Files are read exactly as written and stood up for you in the viewer; the converter has a switch for it, so a model does not arrive in the next program lying on its side.
Convert IGES to another format
Every pairing has a page saying what survives the trip.
Other things to do with an .iges file
Questions about IGES
How do I open an .iges file?
Drop it into the viewer on this site and it opens in the browser, with the scene tree, the materials and the mesh statistics. Nothing is uploaded. If you want it in another program instead, convert it to GLB, which almost everything reads.
Is IGES a good format to archive in?
IGES stores geometry, materials and colour, scene hierarchy. Anything outside that list will not be in the file at all, so archive the original alongside it if the surfacing or the rig matters.
Does converting IGES lose quality?
Geometry is copied vertex for vertex, so the shape does not degrade. What gets lost is whatever the target format has no field for: convert to STL and the materials go, convert to OBJ and the animation goes. The comparison table on each converter page says exactly which.
Formats that hold the same things
Or go back to the full format reference.