Starter
3credits
$7.99
$2.66 each
3 downloads of any size. Good for a one-off project.
Free under 5 MBSTL → IGESNo software installation
Convert STL to IGES online
Convert an STL (.stl) mesh to IGES (.iges or .igs) for legacy CAD/CAM import and surface-based exchange. The IGES result is derived from the STL triangles; it does not recreate smooth NURBS surfaces, sketches, dimensions, constraints or the original feature history.
Encrypted uploads Files up to 300 MB Automatically deleted within 7 days
Upload your STL file
Choose one STL file. This page is already configured to create IGES output.
Drag and drop your STL mesh here
or choose a file from your computer
Browse filesMaximum file size: 300 MB
Files under 5 MB convert and download free. Larger files use one credit for one completed download, regardless of file size.
No STL file available? Try a STL sample to see the conversion workflow.
Pricing
Pay as you go, cheaper by the pack
Files under 5 MB convert and download free. Larger files use one credit for one completed download, regardless of file size. 1 credit downloads any file, any size, and credits never expire.
Save 11%
Pro
5credits
$12.99
$2.60 each
5 downloads of any size. The everyday choice.
Team
10credits
$19.99
$2.00 each
10 downloads of any size. Best balance of price and volume.
Studio
15credits
$26.99
$1.80 each
15 downloads of any size. Lowest price per file.
No desktop software
Start the STL-to-IGES workflow in your browser without installing a CAD application or conversion plugin.
Honest mesh-to-surface output
The IGES result represents geometry derived from the STL facets. It is not presented as a recovered analytic or parametric CAD model.
Ready to inspect
Open the IGES result in the legacy CAD, CAM or surface-modelling application used downstream. Check scale, surface continuity, open edges and file complexity.
Open IGES viewerPrivate file handling
Conversion files stay private, are not added to the public CAD library and are automatically deleted within 7 days.
Continue your workflow
Inspect the STL, verify the IGES or request specialist help
Inspect the source mesh first, validate the IGES result after conversion, or request reverse engineering when the job requires clean analytic surfaces.
Check the source STLCheck the STL for holes, inverted normals, disconnected shells, excessive triangle density and incorrect scale before conversion.Open STL viewerInspect the IGES outputConfirm that the IGES opens at the expected size and contains the expected surfaces, shells or entities.Open IGES viewerNeed smooth CAD surfaces?Ask a CAD designer to rebuild analytic planes, cylinders, fillets and NURBS surfaces when a faceted IGES result is not suitable.Hire a CAD designer
Simple conversion workflow
How to convert STL to IGES online
Move from a triangular STL mesh to an IGES-compatible surface model in three steps.
Upload the STL file
Choose a .stl file up to 300 MB. Watertight, manifold meshes with consistent normals produce the most reliable exchange result.
Convert to IGES
The route is preconfigured for IGES output. Start the conversion without searching through a destination-format menu.
Download and verify
Open the .iges or .igs file in the receiving system. Verify intended units, surface count, gaps and whether the geometry is usable for the next operation.
Format behaviour
What actually happens when STL is converted to IGES?
STL stores only a tessellated surface made of triangles. IGES can store curves, wireframes and trimmed surface entities. During conversion, the mesh facets are translated into IGES-compatible geometry—often many planar or trimmed surface patches. The process cannot infer the original smooth surfaces or design intent.
What is normally retained
- Visible shape defined by the STL triangles
- Mesh vertices and face boundaries
- Model orientation
- Separate connected shells where supported
- Closed volume only when the source is watertight and the converted surfaces sew successfully
What is not retained or may change
- Original sketches, constraints and feature history
- Exact cylinders, planes and other analytic surfaces
- STL unit intent when it was not recorded elsewhere
- Color, materials and textures
- A lightweight solid model; dense meshes can create thousands of IGES entities
STL meshSTL
IGES modelIGESFormat comparison
STL versus IGES
Choose the format according to what the next application needs—not because one is universally better.
| Feature | STL STL | IGES IGES |
|---|---|---|
| Primary use | Slicing, 3D printing and mesh workflows | Legacy CAD/CAM exchange and surface-based workflows |
| Geometry | Triangle mesh | Curves, wireframes and trimmed surface entities |
| Editability | Mesh editing; no feature history | Surface/entity editing, but a mesh-derived IGES remains faceted |
| Units | No standard unit field | Can carry a unit setting, but the source intent must be supplied correctly |
| Visual data | Standard STL does not carry textures or materials | Not intended for texture-rich visualization workflows |
Choose IGES when
A legacy CAD, CAM or supplier workflow specifically requires .igs or .iges
You need an IGES-compatible container for the existing mesh-derived shape
You will validate the result as surfaces rather than assume it is a native solid
A faceted surface result is acceptable for the receiving workflow
Keep STL when
The next step is slicing or 3D printing
You are still repairing or simplifying the mesh
You need to preserve the original triangles
The receiving system already accepts STL
Before continuing
Check the converted IGES before using it
A valid IGES download can still contain thousands of faceted surfaces or open boundaries. Inspect it before machining, quoting or editing.
- 01
Verify units and overall dimensions
STL has no standard unit field. Measure a known feature and confirm the intended millimetre, inch or other scale in the IGES result.
- 02
Check the surface or shell status
Determine whether the receiving application reports separate surfaces, a sewn shell or a closed body.
- 03
Inspect open edges and gaps
Look for holes, overlaps, non-manifold areas and unsewn boundaries inherited from the mesh.
- 04
Review facet density
A dense STL can become a very large IGES with thousands of small surface entities. Confirm the file remains usable.
- 05
Confirm orientation and normals
Check for flipped or missing surface patches after import.
- 06
Test the target CAD/CAM workflow
Open the IGES in the exact legacy CAD, CAM or supplier system for which it was created.
Common problems
STL-to-IGES troubleshooting
Most failures come from damaged meshes, missing unit context or expecting automatic surface reconstruction from triangles.
The IGES looks faceted
Cause: The output follows the triangles in the STL.
Fix: Use the file for compatible exchange, or request a reverse-engineered model when smooth analytic surfaces are required.The model is the wrong size
Cause: STL does not define a standard unit.
Fix: Confirm the intended source unit and rescale in the receiving application.The result contains open surfaces
Cause: The STL has holes, non-manifold edges or disconnected shells.
Fix: Repair and close the mesh before converting again.The IGES is huge or slow
Cause: Each source triangle may generate additional IGES entities.
Fix: Create a copy and reduce non-critical mesh density before conversion.Faces are missing or reversed
Cause: Invalid triangles or inconsistent normals were inherited from the STL.
Fix: Repair faces and recalculate normals in a mesh editor.The file is difficult to edit
Cause: Changing the container does not reconstruct native CAD features.
Fix: Use the result for exchange or inspection; commission a native rebuild for design changes.Secure processing
Your design files remain yours
Engineering files can contain confidential product geometry and documentation. Marathon OS keeps conversion uploads separate from its public CAD library and explains how each file is handled.
Encrypted transfer
Files are transferred over an encrypted connection.
Automatic deletion
Uploaded source files and converted outputs are automatically deleted within 7 days.
You retain ownership
Uploading or converting a file does not transfer ownership of the design to Marathon OS.
Never published automatically
Conversion files are not listed in the public Marathon OS CAD library.
Popular CAD conversion workflows
Explore a small set of adjacent engineering, mesh and drawing handoffs.
STEPSTL
STEP to STL
CAD to 3D-printing mesh
IGESSTEP
IGES to STEP
Legacy surfaces to modern CAD exchange
STLSTEP
STL to STEP
Mesh to CAD exchange
OBJSTL
OBJ to STL
Mesh handoff for slicing
3DMSTEP
3DM to STEP
Rhino to CAD/CAM exchange
DWGDXF
DWG to DXF
Drawing exchange
Marathon OS Design Hub
Find an existing model before rebuilding one
Search the Marathon OS library for a usable starting model. Review dimensions, licensing and manufacturing suitability before using a downloaded file.
3d-printing
Spool Holder Adapter 2 | 3D CAD Engineering Model
STEP engineering modelFree
3d-printingTmz-E | 3D Engineering Design File
STEP engineering modelFree
3d-printing69 Pulley Gt2 3D Print Cnc Fusion 360 Pistacchio Graphic | 3D CAD Engineering Model
STEP engineering modelFree
3d-printingLaser Tree Dovetail Mount for CNC Laser Systems
STEP engineering modelFree
3d-printingFdm 70Mm 1 | Professional CAD Design
STEP engineering modelFree
3d-printing3D Printable Sleeve for Vortec V900 Seatpost and Handlebar
STEP engineering modelFree
Frequently asked questions
Frequently asked questions about STL to IGES conversion
Clear answers about output behaviour, compatibility, pricing, file limits and privacy.
How do I convert STL to IGES online?
Upload the STL file (.stl), confirm IGES as the preselected output, start the conversion and download the IGES result (.iges, .igs). Verify it in the application used for the next workflow.
Why convert STL to IGES?
Use this conversion when an older CAD, CAM or supplier system requires IGES and does not accept the original STL directly. The result remains based on the mesh geometry.
Will STL to IGES create smooth editable CAD surfaces?
Not automatically. The IGES is derived from the STL triangles and may contain many faceted surface patches. Smooth NURBS or analytic surfaces require reverse engineering or a native rebuild.
Which STL and IGES extensions are supported?
This route accepts .stl input and creates .iges, .igs output.
Is the STL to IGES converter free?
Files under 5 MB can be converted and downloaded free. Larger files use one credit for one completed download.
What is the maximum STL file size?
You can upload a STL file up to 300 MB. High triangle counts can create much larger IGES files with many individual entities.
How are my files handled?
Files are transferred securely, are not published to the public CAD library and are automatically deleted within 7 days. You retain ownership of the uploaded design.