How do I convert IGES to STL without CAD software?

Drop the .iges or .igs file in the box above. The page loads the open-source Open CASCADE geometry kernel as WebAssembly, reads the surfaces, turns them into triangles at the quality you pick and gives you a binary STL. It all runs in your browser tab.

Is IGS the same as IGES?

Yes. .igs and .iges are two extensions for the same Initial Graphics Exchange Specification format, and both open here.

Is my IGES file uploaded?

No. The file is read and converted on your own computer. Nothing is sent to our servers, there is no account and no credits are used.

What units does the STL use?

Millimetres, which is what slicers expect. The converter reads the unit from the IGES header and scales to millimetres, so a part drawn in inches comes out 25.4 times larger in numbers but the right physical size. The panel shows the unit it found.

Which quality should I pick?

Quality sets how far a flat facet may stray from the true curved surface. Normal is right for most prints. If round holes or fillets look faceted in the slicer, convert again with Fine. Coarse makes the smallest file and is best for large, mostly flat parts.

Why does my STL have holes or fail to slice?

Many IGES files are a collection of separate surfaces, not one closed solid, and the exporting program may leave tiny gaps between them. Those gaps carry over into the STL. Re-export from CAD as a solid if you can, or open the STL in a repair tool before slicing.

Can I keep the parts separate?

Yes. The parts list shows every body or surface group in the file. Untick the ones you do not need, then download one STL with everything, or a ZIP with one STL per part. Parts keep their positions so they still line up.

Can I convert IGES to OBJ or GLB too?

Yes. After converting you can download OBJ (one object per part) or GLB (with part colours) for 3D apps, game engines and web viewers. Both are written Y-up, which those apps expect; the STL keeps the CAD Z-up for slicers.

Should I export IGES or STEP from my CAD program?

For a part you will 3D print, STEP or STL from the CAD program is usually cleaner, because STEP keeps solids closed. Use IGES when it is the only file you have, for example from an older supplier library. If you have a STEP file, use our STEP to STL converter.

IGES to STL Converter: Free, Online, In Your Browser

What is an IGES file?

IGES (Initial Graphics Exchange Specification) is one of the oldest neutral CAD formats. It was first published in 1980 under the US National Bureau of Standards (now NIST) so that different CAD systems could swap drawings and 3D geometry. The last version, 5.3, came out in 1996; since then STEP has taken over most new work, but IGES files are still everywhere in supplier libraries, tooling and CAM.

An IGES file is plain text in fixed 80-character lines, split into Start, Global, Directory and Parameter sections. The Global section names the sending system and the unit; each entity is a line, arc, NURBS curve, NURBS or trimmed surface, or (in newer files) a B-rep solid. Both .igs and .iges are the same format.

A 3D printer cannot use those exact surfaces directly. The slicer needs a triangle mesh, which is what STL is. This converter tessellates every surface into triangles at the quality you choose and writes them in millimetres.

IGES exports from common CAD programs such as SolidWorks, Autodesk Inventor, CATIA, Siemens NX, Rhino and FreeCAD open here, as do older files from supplier part libraries.

IGES vs STEP vs STL

	IGES (.igs, .iges)	STEP (.stp, .step)	STL (.stl)
What it stores	Exact curves and surfaces (NURBS, trimmed surfaces), sometimes solids	Exact solids and surfaces with assembly structure, colours and metadata	Only triangles: a faceted copy of the outer surface
Standard	IGES 5.3 (1996), a US national standard no longer developed	ISO 10303, still updated (AP203, AP214, AP242)	De facto format from 3D Systems (1987)
Units	Stored in the file header	Stored in the file	None: slicers assume millimetres
Typical use	Older CAD exchange, surface models, tooling, CNC and CAM	Modern CAD exchange between programs	3D printing and slicers
Editable in CAD	Yes (surfaces may need repair or knitting)	Yes, usually as clean solids	Hard: a mesh, not features
Watertight	Not always: many IGES files are separate surfaces	Usually, when exported as solids	Only if the source was closed

In short: IGES and STEP keep exact CAD geometry and are what you edit; STL is the triangle copy a slicer prints. Have a STEP file instead? Use the STEP to STL converter.

How to convert IGES to STL for 3D printing

1
Export IGES from CAD
In your CAD program choose File, Export (or Save As) and pick IGES (.igs or .iges). Solids or trimmed surfaces both work.
2
Drop the file here
Add the .iges or .igs above. The CAD kernel (a few MB) downloads the first time, then the file is read in your browser.
3
Pick the quality
Normal suits most prints. Fine makes round holes and fillets smoother; Coarse keeps big flat parts small.
4
Check the parts and size
Turn off parts you do not want to print, and check the size in millimetres against a dimension you know.
5
Download and slice
Save a binary STL (or one STL per part in a ZIP) and open it in your slicer. OBJ and GLB are there for other 3D apps.

What gets converted, and the limits

Surfaces and solids are converted. Curves, points, drawings, dimensions and annotations have no surface to print, so they are skipped.
Many IGES files are a set of separate surfaces rather than one closed solid, so the STL can have small gaps where surfaces meet. If your slicer reports holes, run it through the STL repair tool.
The output is in millimetres, converted from the unit in the file header (an inch file is scaled by 25.4).
Files up to 50 MB are accepted. A conversion that would produce more than 4 million triangles stops with a message to use Coarse.
Compressed (.igs with a C section) and binary IGES are rare and not supported. STEP files go to the STEP to STL converter.

Slicer reports holes or open edges? Repair the STL, then check it in the STL viewer.

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Program names are trademarks of their owners and are used only to describe file compatibility; The3DAI is not affiliated with or endorsed by them. The conversion uses the open-source Open CASCADE Technology kernel (LGPL-2.1).

IGES to STL Converter