Find out what is wrong in four steps
- Try the file in the viewer. Drag the DWG onto the viewer at the top of this page. If it opens here, the file is fine and the problem is the program you tried first.
- Check which version saved it. Open the DWG in Notepad and read the first six characters. AC1032 is the 2018 format, used by AutoCAD 2018 and every release since; AC1027 is 2013 (AutoCAD 2013 to 2017), AC1024 is 2010, AC1021 is 2007, AC1018 is 2004, AC1015 is 2000.
- Match the fix to the cause. A newer version than yours: ask the sender to save it in an older format, or convert it yourself (see below). No readable version code, or the viewer cannot open it either: the file is probably damaged.
- If parts are missing, add them. When the drawing opens but looks incomplete, it usually refers to other files (xrefs) or fonts that are not on your computer. The viewer names them and lets you add them from your disk.
Double-clicking does nothing, or Windows asks which app to use
Windows has no built-in program for DWG files. Without AutoCAD or another CAD program, double-clicking a DWG either does nothing useful or asks you to pick an app. Nothing is wrong with the file; you only need something that can read it.
For looking at a drawing, measuring it or printing it to PDF, the viewer on this page is enough. If you open DWG files often, the portable desktop version of the same viewer can be set as the program for .dwg files under “Open with”.
AutoCAD says the drawing file is not valid
An AutoCAD release can open drawings saved in its own format and older ones, but not newer ones. Autodesk's own example: AutoCAD 2015 cannot open a drawing saved in the 2018 format. Older releases often report this as “Drawing file is not valid”, a message that can also mean the file is damaged, so check the version code first.
Ways around it: ask the sender to save the drawing again in an older format (Save As, then choose the older format under file type); convert it yourself with DWG TrueView, Autodesk's free viewer, which includes DWG Convert for this; or, if you only need to look at it, open it in the viewer here, which reads the 2018 format.
When the file itself is damaged
A drawing can be damaged by an interrupted download, an e-mail system that altered the attachment, or a crash while it was being saved. Signs are a file with no readable version code, a file much smaller than expected, or a file that no program can open.
Download it again, or ask the sender to put it in a ZIP file before sending, which protects it on the way. In AutoCAD, the RECOVER command tries to repair a damaged drawing. AutoCAD also keeps the previous save as a .bak file in the same folder; copy it, rename the copy to .dwg and open that.
It opens, but looks wrong
Missing parts usually come from external references: the drawing points to other DWG files, such as a title block or a site plan, that were not sent with it. Text in the wrong font comes from fonts that are not installed. In both cases the viewer shows a notice and lets you add the missing files from your computer; they are used locally and never uploaded.
Very large drawings can be more than a browser can handle. Purging unused content in AutoCAD, or splitting the drawing, makes the file smaller.
Still not opening? Send it to us
When the viewer cannot open a drawing, it offers to send that one file to us so we can find out why. Nothing is sent unless you confirm, the file is used only to fix the problem and it is deleted after three months.
Frequently asked questions
- Why won't my DWG file open?
- Usually because there is no CAD program on the computer, because the drawing was saved by a newer AutoCAD than the one you have, or because the file is damaged. Opening it in a browser-based viewer quickly tells you which.
- How do I open a DWG from a newer version of AutoCAD?
- Ask the sender to save it in an older DWG format, convert it with Autodesk's free DWG TrueView (DWG Convert), or view it in a viewer that reads the current 2018 format, such as the one on this page.
- How can I tell which AutoCAD version saved a DWG?
- Open the file in Notepad. The first six characters are the format code: AC1032 means the 2018 format (AutoCAD 2018 and later), AC1027 the 2013 format, AC1024 the 2010 format.
- What does “Drawing file is not valid” mean?
- AutoCAD could not read the file. Most often it was saved by a newer AutoCAD release than yours; it can also mean the file is damaged. Check the version code in Notepad to tell the two apart.
- How do I repair a damaged DWG file?
- Download it again or ask for it in a ZIP file. In AutoCAD, run RECOVER on the file, or rename the .bak file in the same folder to .dwg and open that copy.