Free online DWG to IGES converter

A CNC, inspection, or legacy CAD system may accept IGES but not DWG, requiring a geometry-only exchange file. The conversion also lets teams send editable curves, surfaces, or limited solid geometry without distributing the original authoring file.

What the DWG format is

DWG is Autodesk’s proprietary binary CAD format, used natively by AutoCAD and supported by applications such as BricsCAD, DraftSight, Civil 3D, and many architectural and mechanical CAD systems. A DWG may contain 2D lines, arcs, blocks, dimensions, hatches, and annotations, or 3D solids, surfaces, meshes, and related metadata.

DWG is common in architectural plans, manufacturing drawings, survey data, and engineering archives. Its contents depend on the producing application: a file that looks like a 3D model may contain only 2D projections, proxy objects, or application-specific entities that another converter cannot interpret.

What the IGES format is

IGES, stored with the .igs or .iges extension, is a neutral CAD exchange format. Common IGES entities include wireframe curves, trimmed surfaces, and some boundary-representation solid data. It is widely supported by older and cross-vendor CAD, CAM, CNC, and inspection systems, and IGES files are commonly represented as human-readable ASCII text.

IGES is useful when the recipient needs editable geometry rather than a rendered image. It does not reliably preserve DWG layers, blocks, paper-space layouts, associative dimensions, constraints, parametric history, text styles, hatch patterns, or application-specific metadata. For modern solid-model exchange, STEP is usually preferable because software generally handles solids, assemblies, and product structure more consistently.

How to convert DWG to IGES

Using Rhino

Rhino is a practical desktop choice for DWG files containing 2D curves, surfaces, or supported 3D geometry.

1. Make a copy of the DWG. Check its units, coordinate system, model-space contents, and whether it contains genuine 3D solids or only 2D drafting entities.
2. Clean the source in the authoring CAD application when possible. Use commands such as AUDIT, remove unused content, and delete proxy objects or construction geometry that the recipient does not need.
3. In Rhino, choose File → Open and select the .dwg file. In the import dialog, select the source units and retain only the required layers and objects.
4. Inspect the imported model. Use SelBadObjects to find invalid geometry, remove duplicate curves, and use Join only where edges should form continuous curves or surfaces. Confirm that solids remain closed with Rhino’s object and geometry checks.
5. Select the required objects and choose File → Export Selected, or choose File → Export for the complete model.
6. Set the output type to IGES (*.igs; *.iges). Choose the IGES entity and unit options required by the receiving system, then save the file.
7. Reopen the exported file in Rhino or, preferably, the recipient’s CAD, CAM, or inspection application. Check scale, units, curve continuity, surface seams, normals, and missing objects.

A 2D DWG normally produces IGES curves and possibly basic annotation entities; it does not become a 3D part. A 3D DWG may export as trimmed surfaces or as solids only when the importer and exporter support the relevant DWG and IGES entities.

Using a CAD translator or mechanical CAD system

A dedicated translator such as CAD Exchanger Desktop can be suitable when its installed version lists both DWG import and IGES export. Mechanical CAD systems may also work, but support varies: some import DWG only as 2D drawing entities, while others can read supported 3D solids or surfaces. Confirm the actual import result before exporting.

Open the DWG, set the source units, suppress unwanted drawing objects, repair gaps or invalid faces, and export through the application’s File → Export or equivalent command. If the destination needs a watertight manufacturing model, test the exported geometry in that destination system rather than assuming that a successful file export produced a usable solid.

Using an online converter

For a simple, non-confidential file, a cloud service such as CAD Exchanger Cloud may be convenient. Verify that the current service interface explicitly supports DWG as input and IGES as output, because format availability and 3D support can change by plan or service version.

1. Check the service’s supported DWG entities, maximum file size, retention policy, and handling of 3D solids.
2. Upload the file, select IGES as the output format, and start the conversion.
3. Download the result and inspect it in a desktop CAD application or the receiving system.

Do not upload proprietary designs without approval. Browser converters may omit proxy objects, layers, layouts, annotations, hidden geometry, or 3D solids, and a download that completes successfully does not prove geometric accuracy.

Quality and compatibility limits

• Geometry is not the drawing: IGES may carry curves, surfaces, and limited solid information, but it is not a reliable replacement for DWG layouts, dimensions, notes, title blocks, or design history.
• IGES export can split a solid into trimmed surfaces. The receiving application may need to stitch or heal those surfaces before machining, mass-property calculation, or further modeling.
• Check the unit system in both applications. IGES includes unit information, but importers can apply the wrong scale or interpret ambiguous source units.
• Inspect for gaps, duplicate curves, self-intersections, tiny sliver faces, disconnected edges, incorrect surface normals, and missing proxy objects.
• Preserve the original DWG. If the recipient needs tolerances, dimensions, notes, or sheet layouts, provide a PDF or native drawing file in addition to the IGES geometry.
• For assemblies, parametric parts, or production-grade solid exchange, request STEP when the receiving system supports it.