Free Online IGS to STL Converter
Convert IGES CAD files to STL for 3D printing. NURBS surface tessellation with accurate mesh output. No CAD software install required.
How to Convert IGS to STL
Upload Your IGS File
Drag and drop your .igs or .iges file onto the converter above, or click to browse. Your file is processed securely and never stored permanently.
Automatic Tessellation
The converter tessellates the NURBS surface geometry from your IGES file into triangle meshes, producing a watertight STL model ready for 3D printing.
Download Your STL
Once conversion is complete, download your STL file and open it in any 3D printing slicer like Cura, PrusaSlicer, or Bambu Studio.
Why Choose Our Converter
Free & No Sign-Up
Convert IGS to STL for free with no registration, no watermarks, and no hidden costs. Convert as many CAD files as you need.
NURBS to Mesh
The converter transforms precise NURBS surface data from IGES files into printable triangle meshes suitable for 3D printing.
3D Printing Ready
The output STL file is compatible with all major 3D printing slicers including Cura, PrusaSlicer, Bambu Studio, and IdeaMaker.
No CAD Software Needed
Convert IGES files without installing SolidWorks, Fusion 360, or FreeCAD. Perfect for quick conversions on any device.
3 Ways to Convert IGS to STL
Choose between online conversion, FreeCAD, or Fusion 360 based on your needs.
Online IGS to STL Converter (This Tool)
Best for: quick, no-install conversion
- Drag and drop your .igs or .iges file onto the converter above.
- Wait for the automatic tessellation to complete.
- Download the STL file and open it in your slicer.
Pros: Free, no software install, works on any device, fast for most files.
Cons: Requires internet connection. NURBS tessellation quality depends on source file complexity.
FreeCAD (Free Desktop CAD)
Best for: full control over mesh density
- Download and open FreeCAD (free, open-source).
- Go to File > Import and select your .igs file.
- Switch to the Mesh Design workbench.
- Select the model and use Part > Create mesh from shape.
- Export the mesh as STL.
Pros: Free and open-source. Full control over mesh density and tessellation quality. Handles complex CAD files.
Cons: Requires downloading and installing FreeCAD. Steeper learning curve for new users.
Fusion 360 (Professional CAD)
Best for: engineering workflows
- Open Autodesk Fusion 360 (free for personal use).
- Go to File > Open and select your .igs file.
- Right-click the body and select Save As STL.
- Choose mesh refinement and save.
Pros: Professional-grade tessellation. High-quality mesh output. Widely used in engineering.
Cons: Requires Fusion 360 account. Free tier has limitations.
Quick Checks Before You Convert
NURBS-to-mesh conversion requires careful preparation for best 3D printing results.
Surface vs Solid
IGES files may contain open surfaces (not closed solids). Open surfaces produce non-watertight meshes that need repair before 3D printing. Check for gaps in your CAD model before converting.
Tessellation Quality
NURBS-to-mesh conversion involves approximation. Lower tessellation = coarser mesh (faster but blocky). Higher tessellation = smoother mesh (larger file). Choose based on your print resolution needs.
File Complexity
Complex CAD models with many surfaces can produce very large STL files. Consider simplifying the model or reducing detail in your CAD software before conversion.
Units and Scale
IGES files store units information. Verify that the converted STL has the correct dimensions in your slicer before printing. Metric units (mm) are standard for 3D printing.
IGS vs STL Format Comparison
| Feature | IGS (IGES) | STL |
|---|---|---|
| Full name | Initial Graphics Exchange Specification | Standard Triangle Language |
| Geometry type | NURBS surfaces (precise) | Triangle mesh (approximated) |
| Accuracy | Mathematical precision | Faceted approximation |
| File size | Large (ASCII text) | Compact (binary) |
| Color / material | No | No |
| Parametric data | No (surfaces only) | No |
| Primary use | CAD data exchange | 3D printing |
| Slicer support | No | Universal |
Fixing Common Issues After Conversion
Typical errors after IGS to STL conversion and how to resolve them.
STL file has gaps or holes
The IGES file contains open surfaces. Use Netfabb, MeshMixer, or MeshLab to repair holes and close the mesh. Most slicers also have built-in mesh repair tools.
Model surface looks faceted or blocky
The tessellation resolution was too low. Convert again with higher mesh density, or use FreeCAD/Fusion 360 to control the tessellation parameters directly.
STL file is extremely large
The model has too many triangles. Use MeshLab's Simplification filter (Quadric Edge Collapse Decimation) to reduce triangle count to 100K-500K for 3D printing.
Slicer shows incorrect dimensions
The IGES file may use different units (inches vs mm). Check the original CAD file's unit settings. Most slicers default to millimeters. Scale the model in the slicer if needed.
What Is an IGES File?
IGES (Initial Graphics Exchange Specification, pronounced "eye-jess") is a vendor-neutral CAD file format developed in 1980 by the U.S. National Bureau of Standards. It uses the .igs or .iges extension and stores precise CAD geometry — NURBS surfaces, B-rep solids, curves, and 2D/3D drawings — as human-readable ASCII text.
IGES was the original cross-CAD exchange format, enabling engineers to transfer models between SolidWorks, Autodesk Inventor, CATIA, NX, Creo, and other CAD systems. It has largely been superseded by STEP (.stp) for new workflows, but remains widely used in manufacturing, aerospace, and automotive industries with large archives of legacy IGES files.
IGES vs STL: why convert?
IGES stores precise CAD surfaces (NURBS, B-rep) that define mathematically smooth geometry. STL stores only faceted triangle meshes. Converting IGES to STL tessellates the smooth CAD surfaces into triangles, producing a mesh ready for 3D printing, mesh editing, or simulation. This conversion requires server-side CAD processing — it cannot be done in a browser.
Last updated: August 2026. Format details reference the IGES specification and the STL file format overview.
Frequently Asked Questions
How do I convert IGS to STL?
Upload your .igs or .iges file using the converter above. The tool automatically tessellates the NURBS surfaces into triangle meshes and produces an STL file. Once conversion is complete, download the STL file.
Is this IGS to STL converter free?
Yes, completely free. No registration, no watermarks, no hidden costs. Convert as many IGS files to STL as you need.
What is the difference between IGS and STL?
IGS (IGES) stores precise NURBS surface definitions for CAD workflows. STL stores approximated triangle meshes for 3D printing. IGS preserves mathematical surface accuracy; STL converts those surfaces into faceted triangles. You need STL for 3D printing because slicers cannot read NURBS data directly.
How do I convert IGES to STL in FreeCAD?
Open FreeCAD, go to File > Import and select your .igs file. Switch to the Mesh Design workbench. Select the imported shape, then use Part > Create mesh from shape. Adjust the tessellation settings, then export the result as STL.
How do I convert IGES to STL in Fusion 360?
Open Fusion 360 and import your .igs file. Right-click the body in the browser and select Save As STL. Choose the mesh refinement level (Low, Medium, High) and save the STL file.
Can I convert IGS to STL without CAD software?
Yes. Our online converter processes IGS files without requiring SolidWorks, Fusion 360, or FreeCAD to be installed. Simply upload your file and download the STL result.
Why does my converted STL look faceted?
NURBS-to-mesh conversion uses tessellation, which approximates smooth surfaces with flat triangles. Lower tessellation density produces more visible facets. Use higher mesh density for smoother results, or use CAD software like FreeCAD to control tessellation parameters precisely.
Are my files uploaded to a server?
Files are processed through our conversion pipeline. They are not permanently stored and are deleted after processing. Your CAD data is never shared with third parties.
Can I convert IGS to STL on Mac?
Yes. Our online converter works in any browser on macOS. Alternatively, download FreeCAD or Fusion 360, both of which are available for Mac and can convert IGES to STL natively.
What IGS files can be converted to STL?
Any IGES file containing surface or solid geometry can be converted to STL. This includes files from SolidWorks, CATIA, NX, Creo, Rhino, and AutoCAD. Files with only 2D drawings or annotations cannot be converted to 3D meshes.
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