If you use AutoCAD or regularly receive drawings from architects, engineers or construction teams, you’ll probably recognise the .dwg file extension.
DWG is the native file format used by AutoCAD and one of the most common formats for storing and exchanging drawing data. Unlike a PDF, which is usually shared when someone needs to view or print a drawing, a DWG can hold the information needed to continue working on it.
So, what exactly is inside a DWG file? And when should you use DWG rather than DXF or PDF? In this guide, we’ll look at what DWG files are, how to open them and which format makes sense for different situations.
What is a DWG File?
A DWG is a digital drawing file capable of storing both 2D and 3D design data. It is most closely associated with AutoCAD, where .dwg is the native file format used to save drawings. A DWG can contain information such as:
- 2D geometry
- 3D geometry
- Layers
- Blocks
- Dimensions
- Text and annotations
- Linetypes
- Drawing properties
- Metadata
- Maps and images
What is stored will depend on the drawing itself. A simple floor plan and a detailed engineering drawing may both be DWG files, but the information within them could be very different.
What Does DWG Stand For?
DWG is commonly associated with the word drawing, which gives a fairly good indication of what the format is used for.
You’ll recognise a DWG file by the .dwg extension at the end of its filename, for example:
- floor-plan.dwg
- building-layout.dwg
Autodesk introduced DWG with the first release of AutoCAD in 1982. It has since become a familiar file format across architecture, engineering, construction, manufacturing and other industries that work with technical drawings.
What Are DWG Files Used For?
DWG files are generally used when drawing information still needs to be worked with rather than simply viewed.
For example, an architect might use a DWG for a detailed floor plan containing layers, dimensions and annotations. An engineer could use one for technical drawings that need to be updated as a project develops.
You’ll commonly find DWG files being used for:
- Architectural plans
- Building layouts
- Engineering drawings
- Infrastructure drawings
- Mechanical drawings
- Manufacturing information
- Building services layouts
- 2D drafting
- 3D design information
Because the drawing data remains editable, a DWG can move between different stages of a project as information is added, checked and updated.
How Do You Open a DWG File?
If you need to create or edit the drawing, AutoCAD is the most obvious place to start.
As DWG is AutoCAD’s native format, you can open a drawing and work directly with its contents. Depending on the file, that could mean changing geometry, managing layers, editing dimensions and annotations, taking measurements or preparing the drawing for plotting.
But having a DWG file doesn’t necessarily mean you need the full AutoCAD desktop application. If all you need to do is look at a drawing, there are other options.
How Can You View a DWG File Without AutoCAD?
Autodesk provides several ways to access DWG files without installing the full desktop version of AutoCAD.
Autodesk Viewer
Autodesk Viewer works through a web browser and supports a wide range of 2D and 3D file formats, including DWG.
It can be useful when you want to review a design without installing desktop software, particularly when drawings need to be shared with colleagues, clients or other project stakeholders.
DWG TrueView
DWG TrueView is Autodesk’s free Windows application for working with DWG files when you don’t need AutoCAD’s full drawing and editing toolset. It can be used to open and view drawings, plot files, create PDFs and convert DWG files between supported AutoCAD drawing formats.
This can be particularly useful if someone has sent you a drawing saved in a newer DWG format than the version of AutoCAD you normally work with.
AutoCAD Web
AutoCAD Web gives you browser and mobile access to DWG drawings.
Rather than being limited to viewing, it includes tools for reviewing, marking up and editing drawings, making it useful when you need access to a DWG away from your main desktop setup.
Which option is right for you comes down to what you actually need to do. If you’re only checking a drawing, a viewer may be enough. If you’re regularly creating and editing drawings, AutoCAD provides the more complete set of tools.
DWG vs DXF: What’s the Difference?
DWG and DXF often appear in the same workflows, but they aren’t quite the same thing.
DWG is AutoCAD’s native drawing format. It is commonly used as the working file when creating and editing drawings.
DXF, or Drawing Exchange Format, was developed by Autodesk to help exchange drawing data between different applications.
In practice, you might work on a drawing as a DWG and export a DXF when the drawing needs to be transferred to another application or workflow.
| DWG | DXF |
| Native AutoCAD drawing format | Drawing exchange format |
| Commonly used as a working file | Commonly used for exchanging drawing data |
| Supports 2D and 3D drawing information | Supports 2D and 3D drawing information |
| Binary format | Can use ASCII or binary data |
| Often produces smaller files | ASCII DXF files can be larger |
| Best suited to DWG-based workflows | Useful where wider data exchange is required |
You don’t necessarily have to choose one format for an entire project. There are plenty of workflows where DWG is used for day-to-day drawing work and DXF is exported when required.
DWG vs PDF: Which Should You Use?
DWG and PDF serve a much more clearly defined set of purposes.
If someone needs to work with the drawing, DWG is usually the more appropriate option. If they simply need to see, review, print or distribute it, PDF is often more convenient.
| DWG | |
| Contains editable drawing data | Primarily intended for viewing and distribution |
| Can retain layers, geometry, blocks and other drawing information | Usually presents a fixed representation of the drawing |
| Requires compatible software for full editing | Can be opened on most computers and mobile devices |
| Useful for ongoing design work | Useful for review, approval and printing |
| Suitable for exchanging working drawings | Easier to send to people who don't use AutoCAD |
For example, you might send another designer the DWG so they can continue working on the drawing, while sending the client a PDF to review.
It’s common to keep the DWG as the working or source drawing and produce PDFs when information needs to be issued more widely.
Why Won’t My DWG File Open?
Sometimes a DWG won’t open even though you have AutoCAD installed. One possible reason is DWG version compatibility.
Different releases of AutoCAD have introduced different DWG file formats. Newer versions of AutoCAD can generally open older DWG formats, but an older version may not be able to open a file saved in a newer format.
For example, Autodesk currently uses the AutoCAD 2018 DWG format across AutoCAD releases from 2018 through 2027. If you’re working with an older version of AutoCAD, you may therefore need the drawing to be saved to an earlier DWG format.
DWG TrueView can also be used to convert DWG files between supported AutoCAD drawing formats.
It’s worth remembering that version compatibility isn’t the only possible cause of a file failing to open. Damaged files, missing references or problems with the drawing itself can also cause issues.
What is TrustedDWG?
You may see a TrustedDWG notification when opening a drawing in AutoCAD or other Autodesk software.
TrustedDWG technology checks whether a drawing was last saved using Autodesk software or software based on Autodesk’s RealDWG technology.
If the file was last saved by another application, AutoCAD may display a warning about potential compatibility or file integrity issues. That warning doesn’t automatically mean the drawing is damaged or unusable. It gives you additional information about where the file has come from before you continue working with it.
Work with DWG Files in AutoCAD
Understanding what a DWG file contains is a useful starting point. The next step is knowing how to manage that information efficiently in AutoCAD.
Layers, blocks, dimensions, layouts and annotations all play a part in keeping drawings accurate and easy to work with, particularly as files become larger or pass between different people.
TMS CADCentre is an Autodesk Partner and Autodesk Authorised Training Centre. We can help you choose the right Autodesk software for your business, as well as support you once it’s in place.
We also offer instructor-led AutoCAD training, available live online or in person at our Larbert training centre. Whether you’re getting started with AutoCAD or looking to build on existing skills, speak to our team to find out how we can help.
Frequently Asked Questions About DWG Files
Do I need AutoCAD to open a DWG file?
No. If you only need to view a DWG, Autodesk offers alternatives including DWG TrueView, Autodesk Viewer and AutoCAD Web.
For regular drawing creation and more extensive editing, AutoCAD provides the full desktop toolset.
Can I open a DWG file online?
Yes. AutoCAD Web provides browser-based access to DWG files, while Autodesk Viewer can be used to view supported design files online.
Can I convert DWG to PDF?
Yes. AutoCAD and DWG TrueView can both be used in workflows where you need to create a PDF from a DWG drawing.
PDF is usually the better choice when the recipient only needs to view, print or review the drawing rather than edit the underlying design.
Is DWG better than DXF?
Neither format is automatically better. DWG is generally the more practical choice when you’re working directly in AutoCAD and want to retain the drawing as your working file. DXF can be useful when exchanging drawing information with other applications.
Is DWG better than PDF?
Again, it depends on what you need the file for. Choose DWG when someone needs access to editable drawing data. Choose PDF when the priority is straightforward viewing, reviewing, printing or distribution.
