DWG versions: codes, years and compatibility

DWG versions are identified by a six-character code such as AC1032 stored in the first bytes of the file; each code covers a group of AutoCAD releases that share one file format. Knowing the code tells you which programs can open the drawing and whether you need to save it down. This page lists every code with its AutoCAD release and year, and shows how to check and change the version.

DWG version codes: the full table

Autodesk changes the DWG format every two or three releases and keeps it stable in between. The table maps each internal code to the AutoCAD releases that write it. Years are the release years of the first AutoCAD version in each group.

The very first release, AutoCAD 1.0 (1982), used the code MC0.0. Pre-R13 codes are reconstructed from the LibreDWG and ODA documentation and vary slightly between sources. Since 2018 the format has not changed: a "DWG 2020", "DWG 2022" or "DWG 2026" file is AC1032, the same format as 2018, so any program that opens 2018 drawings opens all of them.

Which DWG version is my file?

The version code is the first six bytes of the file, in plain ASCII, so you do not need CAD to read it:

1. Any OS: open the .dwg in a text editor (Notepad, TextEdit, VS Code) and look at the first characters. Everything after AC1032 will be binary noise; do not save the file.
2. macOS / Linux terminal: head -c 6 drawing.dwg
3. Windows PowerShell: [Text.Encoding]::ASCII.GetString((Get-Content drawing.dwg -Encoding Byte -TotalCount 6))
4. AutoCAD: when you open a drawing, the command line prints "Opening an AutoCAD 2013 format file" (or whichever version it is).

Look the code up in the table above. If the first bytes are not AC followed by digits, the file is not a DWG at all; a PDF, a ZIP or a DXF renamed to .dwg is a common cause of a "not valid" error, covered in fix a DWG file that will not open.

Compatibility: which AutoCAD opens which DWG

Compatibility is one-directional. Every AutoCAD release opens every earlier DWG version back to R2.5 and silently upgrades it on save. No AutoCAD release opens a DWG newer than itself: AutoCAD 2013 refuses an AC1032 file with "Drawing file is not valid" or "was created by a newer version", and AutoCAD 2010 refuses AC1027. The same logic applies to BricsCAD, LibreCAD, Visio's CAD import and other DWG readers; each has a newest version it understands.

So the rule for sharing is: find out the oldest program on the receiving end and save in a version it reads. When in doubt, AutoCAD 2013 (AC1027) is a safe choice, since it is read by every DWG tool released in the last decade; AutoCAD 2000 (AC1015) is the widest common denominator short of R12.

How to save a DWG in an older version

In AutoCAD or AutoCAD LT:

1. Run SAVEAS (File > Save As).
2. Open the Files of type list and pick a version: "AutoCAD 2013/LT2013 Drawing (*.dwg)", "AutoCAD 2010/LT2010 Drawing", "AutoCAD 2000/LT2000 Drawing", down to "AutoCAD R14/LT98/LT97 Drawing".
3. Save under a new name so the current-version original stays intact.
4. To make this the default, run OPTIONS, open the Open and Save tab and set Save as to the older format.

For many files at once, use DWG Convert inside the free Autodesk DWG TrueView (Windows), which batch-converts whole folders to any version from R14 up, or the free ODA File Converter (Windows, macOS, Linux), which does the same and also converts between DWG and DXF. See DWG to DXF.

What you lose when saving down: features that did not exist in the target version. Dynamic blocks and annotative objects (2006+) become static, multileaders and tables (2008+) and some hatch and MTEXT options are simplified, and custom objects from vertical products turn into proxy graphics. Geometry, layers, dimensions and plain text survive every downgrade back to R14.

DWG TrueView 2026, 2025, 2024: which one do you need?

Autodesk releases a new DWG TrueView every year along with AutoCAD, and the year in the name means "opens every DWG version up to and including this release". Since the format has been AC1032 since 2018, DWG TrueView 2018 through 2026 all open current drawings; the yearly updates bring the newer AutoCAD rendering engine, operating-system support and bug fixes rather than new format support. DWG TrueView 2014 to 2017 stop at AC1027 and will not open files saved by AutoCAD 2018 or later.

Practical advice: download the latest version (DWG TrueView 2026 at the time of writing) from the Autodesk website; it requires a 64-bit Windows and an Autodesk account for the download. There is no macOS or Linux build. If you only need to look at a file on any OS, the viewer on this page opens R14 to 2026 drawings in the browser; the DWG TrueView alternatives page compares the two honestly.

Which DWG versions this viewer opens

The viewer converts the DWG to DXF on your device with LibreDWG, then renders it. It opens AC1014 through AC1032, that is AutoCAD R14 through 2018 and every release since, including 2026. R12 and older (AC1009 and below) are not supported: LibreDWG reads them only partially and cannot write DXF for them, so those files need DWG TrueView or ODA File Converter to be saved up first. Files over 60 MB are skipped to protect browser memory; see open large DWG files. In a test with 18 user-submitted drawings in October 2026, 14 opened; the four failures were two non-DWG files renamed to .dwg and two R11/R12 drawings.

Frequently asked questions