What is a .dwg file?
AutoCAD Drawing · 3D model · Autodesk · 1982
DWG is the native format of AutoCAD and the industry standard for 2D and 3D CAD drawings in architecture and engineering. It is a dense, proprietary format best opened in CAD software or a dedicated viewer.
What is a .dwg file used for?
DWG stores precise vector geometry, layers, dimensions and metadata for technical drawings and models. It is the working format of the CAD world.
Because it is proprietary and version-specific, opening a DWG reliably usually means AutoCAD or a compatible CAD app. Free viewers exist for looking without editing.
DWG is also tied to versions: each AutoCAD release writes its own DWG format, so a drawing saved in a newer AutoCAD may not open in an older program. The version marker sits in the first bytes (for example AC1032 for the 2018 format), and free tools like DWG TrueView can save a DWG down to an earlier version.
For sharing drawings across different software, the more open DXF format is often exported instead.
How to open a .dwg file
The .dwg format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list. For a step-by-step walkthrough, see how to open a .dwg file.
Windows
- AutoCAD
- DWG TrueView
- LibreCAD (via DXF)
macOS
- AutoCAD for Mac
- DWG viewers
Linux
- ODA File Converter
- LibreCAD (via DXF)
Web
- Online CAD viewers
How to convert a .dwg file
You can convert a .dwg file to DXF, PDF using a conversion tool or the export menu of an app that opens it.
.dwg file signature (magic bytes)
Programs recognise a .dwg file by the bytes at the start of the file, not by its name. These are the signatures for DWG. For a full breakdown, see the DWG file signature page.
| Hex signature | Offset | Note |
|---|---|---|
| 41 43 31 30 | 0 | 'AC10' version prefix (e.g. AC1027) |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .dwg file?
DWG is the native format of AutoCAD and the industry standard for 2D and 3D CAD drawings in architecture and engineering. It is a dense, proprietary format best opened in CAD software or a dedicated viewer.
How do I open a DWG without AutoCAD?
Use Autodesk's free DWG TrueView to view and print, or convert the DWG to DXF or PDF for wider access.
How do I convert a DWG to PDF?
Open the drawing in a CAD app or a free viewer like DWG TrueView and use its Plot or Print to PDF option. Online CAD viewers can also export a DWG to PDF without installing anything.
Related formats
Sources
Details on this page were checked against authoritative references: