What is a .iges file?
Initial Graphics Exchange Specification · 3D model · US National Bureau of Standards · 1980
An .iges (or .igs) file is a neutral CAD exchange format for moving precise engineering geometry, curves, surfaces and solids, between different CAD systems. It is one of the oldest and most widely supported CAD interchange formats.
What is a .iges file used for?
IGES is a plain-text format organised into fixed 80-column sections. It carries exact geometry rather than the triangle meshes of formats like STL, which matters for engineering.
It is being succeeded by STEP, which represents more of a model's design intent. Nearly every CAD tool imports IGES; open it in FreeCAD, SolidWorks, Fusion 360 or similar.
How to open a .iges file
The .iges format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list. For a step-by-step walkthrough, see how to open a .iges file.
Windows
- FreeCAD
- SolidWorks
- Autodesk Fusion 360
macOS
- FreeCAD
- Autodesk Fusion 360
Linux
- FreeCAD
- OpenSCAD (via conversion)
How to convert a .iges file
You can convert a .iges file to step, stl, obj using a conversion tool or the export menu of an app that opens it.
.iges file signature (magic bytes)
Programs recognise a .iges file by the bytes at the start of the file, not by its name. These are the signatures for IGES.
| Hex signature | Offset | Note |
|---|---|---|
| (no fixed signature) | 0 | no reliable fixed signature |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .iges file?
An .iges (or .igs) file is a neutral CAD exchange format for moving precise engineering geometry, curves, surfaces and solids, between different CAD systems. It is one of the oldest and most widely supported CAD interchange formats.
How do I open an IGES file?
Use a CAD program: FreeCAD is free and imports IGES, as do SolidWorks and Fusion 360. It is precise geometry, not a mesh.
What is the difference between IGES and STEP?
Both are neutral CAD exchange formats. STEP is newer and carries more design intent (assemblies, metadata); IGES is older but very widely supported.
Is .igs the same as .iges?
Yes. .igs and .iges are the same IGES format; the shorter extension is a historical three-letter version.
Related formats
Sources
Details on this page were checked against authoritative references: