DWG → DXF Converter

A no-fuss Python CLI for converting AutoCAD .dwg files to .dxf (text format that ezdxf, QGIS, GIS pipelines, etc. can actually parse).

Built because:

• libredwg-tools is not packaged on Debian/Ubuntu (you have to build from source — and it's slow and fragile).
• ODA File Converter is a Windows/Mac GUI tool; no clean Linux pipeline.
• Existing Python alternatives are commercial or read-only.

This tool wraps Aspose.CAD for Python (commercial, has a free tier with output watermark for evaluation) and adds:

• Clean CLI: dwg2dxf input.dwg
• Batch mode: dwg2dxf ./drawings/*.dwg --out ./dxf/
• Glob patterns + recursion
• .NET globalization workaround baked in (you don't need to remember the env var)
• Skips already-converted files unless --force
• Honest error messages and progress

Install

pip install dwg2dxf

Or directly:

pip install aspose-cad ezdxf
git clone https://github.com/zheimr/DWG-to-DXF-Converter
cd DWG-to-DXF-Converter
pip install -e .

Usage

# Single file
dwg2dxf my_drawing.dwg
# → my_drawing.dxf

# Specify output
dwg2dxf my_drawing.dwg -o out/drawing.dxf

# Batch (whole directory)
dwg2dxf ./drawings/ --out ./dxf/

# Recursive
dwg2dxf ./projects/ --recursive --out ./dxf/

# Glob
dwg2dxf "site_*.dwg" --out ./dxf/

# Verify result with ezdxf
dwg2dxf my_drawing.dwg --verify

Python API

from dwg2dxf import convert

# Single file
convert('input.dwg', 'output.dxf')

# Batch
from dwg2dxf import batch_convert
results = batch_convert(['a.dwg', 'b.dwg'], output_dir='./dxf/')
print(f"Converted: {results['ok']}, Failed: {results['failed']}")

What works, what doesn't

✅ Works:

• DWG → DXF for AutoCAD 2000+ files
• Most geometry preserved (LINE, POLYLINE, CIRCLE, ARC, ELLIPSE)
• Layer names retained
• Coordinates preserved exactly
• Layouts, blocks, viewports

⚠️ Caveats:

• Default export is DXF R12 (AC1009) — old format. Some entities downgrade:
  • INSERT blocks may become exploded POLYLINEs
  • TEXT / MTEXT may be partially lost
  • Hatches preserved as outlines
• Free Aspose.CAD tier adds a small evaluation watermark to output. Get a license from Aspose for clean output.
• Speed: ~30-90s for a 50MB DWG on a modern CPU (single-threaded).
• Output DXF can be 30-100× larger than the source DWG (text format).

❌ Not supported:

• DWG password protection
• 3D solids (will downgrade to wireframe)
• Custom ARX/ObjectDBX entities

Alternatives to consider

Tool	Open source?	Setup	Output quality
This tool (aspose-cad backend)	❌ (free tier)	pip install	Good, R12 default
libredwg (dwg2dxf)	✅ GPL	Compile from source on Linux	Good, multi-version
ODA File Converter	❌ (free for personal)	Windows/Mac GUI, headless via wine	Best
QCAD CE	✅ GPL	Build from source	Good
AutoCAD SaveAs	❌ paid	Windows	Reference

If you need true open source for production: spend the afternoon building libredwg from source. This tool is for "just need it working today".

Why not libredwg?

Tried. Build hangs on submodule init in standard Docker images, requires swig, autoconf-archive, and CA cert fixes. Not packaged in Debian Stable, Ubuntu 22.04, or Ubuntu 24.04 repos as of mid-2026. If someone gets a clean Dockerfile working, PR welcome — happy to make this a multi-backend tool.

License

MIT — see LICENSE. Note that aspose-cad has its own commercial license; this wrapper code is MIT but the actual conversion happens through Aspose.

Contributing

PRs welcome. Especially want:

• libredwg backend with automatic fallback
• ODA File Converter wrapper (when installed)
• Better DXF version control (currently locked to R12 from Aspose default)
• Conversion options (precision, layer filter, etc.)
• Tests with sample DWG files

Real-world use case

This was extracted from a fiber optic infrastructure GIS project where we needed to extract manhole coordinates from 8 CAD drawings (350 MB total) of a municipal fiber network. After conversion to DXF, we used ezdxf to read polylines on Mobese_EK ODASI_TIP 10 layer and converted CAD coordinates to WGS84 via pyproj. End-to-end pipeline in ~50 lines of Python.

If you have a similar GIS-from-CAD use case and want a tip: AutoCAD drawings are usually in a local projected CRS. You'll need to find one reference point with known WGS84 coordinates to derive the affine transformation. Once anchored, all geometries flow.