How to Open a DWG File: Free Viewers

What is a DWG file?

DWG ("drawing") is Autodesk's native file format for AutoCAD and the wider AutoCAD-compatible CAD ecosystem, storing 2D vector geometry, 3D models, layers, blocks, dimensions, text and metadata for architectural, engineering, mechanical and product-design drawings. It's the de facto standard format across the CAD industry — most other CAD software either supports DWG directly or via conversion.

Unlike an open format, DWG's internal binary layout has never been officially published by Autodesk. Everything third-party tools know about it comes from years of careful reverse engineering, primarily by the Open Design Alliance (a consortium of CAD vendors) and the open-source LibreDWG project. Making things harder still, every DWG file starts with a short, simple, publicly stable version tag — but from AutoCAD 2004 onward, most of the actual drawing data behind that tag is compressed and obfuscated internally, on top of already being undocumented.

How to open a DWG file on a Mac

DWG TrueView is Windows-only, and macOS Preview and Quick Look can't display DWG drawings, so Mac users have these options:

• Autodesk Viewer in Safari or Chrome (above) — free, and the easiest way to just look at a drawing.
• AutoCAD for Mac / AutoCAD LT for Mac — Autodesk's paid Mac versions (a free trial is available), which open and save DWG natively.
• ODA File Converter has a macOS version: convert the DWG to DXF, then open the DXF in a free program such as LibreCAD or QCAD Community Edition, or import it into FreeCAD.
• Adobe Illustrator can open DWG and DXF files directly (File > Open) if you only need the linework for graphics work.
• Other paid CAD programs with Mac versions, such as BricsCAD and QCAD Professional, read DWG directly.

Open a DWG file on iPhone, iPad or Android

Autodesk's own AutoCAD mobile app (listed as "AutoCAD - DWG Viewer & Editor" on Google Play and simply "AutoCAD" in the App Store) opens DWG files from email attachments, the Files app, Google Drive, Dropbox, OneDrive and Autodesk's cloud storage. Viewing, zooming, switching layouts and toggling layers are free with an Autodesk account; drawing and editing tools require a paid subscription after the trial.

1. Install the AutoCAD app and sign in with a free Autodesk account.
2. On iPhone/iPad, tap the .dwg attachment or file, then the Share button, and choose AutoCAD. On Android, tap the file and pick AutoCAD in the Open with list.
3. Alternatively, open viewer.autodesk.com in your phone's browser and upload the file there.

Third-party viewer apps exist as well, but stick to well-known ones from the official app stores, since you'll be giving them access to your drawings.

Fixing "this file is from a future release" or won't-open errors

1. Use the tool on this page to see the file's exact AutoCAD release — e.g. AC1032 means AutoCAD 2018 or newer.
2. If your CAD program predates that release, either update it, or ask whoever sent the file to re-save it in an older format (in AutoCAD: Save As and pick an older DWG version).
3. Without access to the original program, use the free ODA File Converter to batch-downgrade the file to an older DWG version, or convert it to DXF, which almost every CAD program can read.

Common DWG file problems and how to fix them

"This file was created by a newer version of AutoCAD"

A straightforward version mismatch. Check the Overview tab on this page's tool for the exact release, then update your software or use the ODA File Converter to save it down to a version your program supports.

The file opens with missing fonts, line styles or X-refs

DWG files often reference external resources (custom fonts/SHX files, external reference drawings, plot styles) that live in separate files, not inside the DWG itself. Make sure those supporting files are available in the same folder or your program's configured search paths.

The file won't open in anything, or looks corrupted

Use the tool on this page first — if it doesn't recognize any valid DWG version signature at all, the file is either badly corrupted, was never a real DWG (check the Overview tab; it also checks whether it's secretly a PDF, image or ZIP file saved with the wrong extension), or was cut off during a transfer. Try re-downloading or re-exporting it from the source.

How to convert a DWG to PDF for free

To send a drawing to someone without CAD software, or to print it, "plot" it to PDF. In the free DWG TrueView on Windows:

1. Open the drawing and click the Model tab or the layout tab you want (layouts usually contain the title block and are set up for printing).
2. Press Ctrl+P (or click the Plot button) to open the Plot dialog.
3. Under Printer/plotter, choose DWG To PDF.pc3 and pick a Paper size.
4. Set What to plot to Layout (on a layout tab) or Extents (on the Model tab), tick Fit to paper and Center the plot, then click Preview… to check it.
5. Click OK and choose where to save the PDF. For several layouts in one go, use Batch Plot to create a single multi-page PDF.

Lines come out as vectors, so the PDF stays sharp at any zoom. For a JPG or PNG image instead, choose PublishToWeb JPG.pc3 or PublishToWeb PNG.pc3 in the same list. Going the other way — PDF back to editable DWG — needs full AutoCAD (its PDFIMPORT command) or another paid CAD program; the free viewers can't do it.

DWG version codes: which format does your file use?

The first six bytes of every DWG file are a version code. Autodesk changes the format only every few releases, so one code covers several AutoCAD versions. The tool at the top of this page reads this code for you; here's what each common one means and the matching option in AutoCAD's Save As list (each is prefixed "AutoCAD", e.g. AutoCAD 2013/LT2013 Drawing (*.dwg)):

A program can open any file whose code is the same as or older than the newest format it supports. So AutoCAD 2016 opens an AC1027 file but not an AC1032 one, while AutoCAD 2026 still saves AC1032 files that AutoCAD 2018 can open.

Batch-convert to an older version or to DXF with ODA File Converter

1. Download the free ODA File Converter from the Open Design Alliance website (Windows, Mac and Linux versions).
2. Put the drawings in one folder and select it as the Input Folder; choose a different, empty Output Folder.
3. Choose an Output version your software supports (e.g. ACAD2013) and an Output file type (DWG, or DXF for programs like LibreCAD), then click Start.

Is it safe to open a DWG file?

A DWG drawing is data — geometry, layers, text — and viewers like DWG TrueView and Autodesk Viewer don't run code from it. The real risk with CAD files comes from AutoLISP and other script files that can travel alongside them, especially inside ZIP packages: files named acad.lsp, acaddoc.lsp, or with .fas, .vlx or .mnl extensions. Full AutoCAD loads such files automatically from certain folders, and AutoCAD malware has spread this way.

• Before opening a received package in AutoCAD, look through the folder and delete any .lsp, .fas, .vlx or .mnl file you weren't expecting.
• Keep AutoCAD's SECURELOAD setting at its default, so AutoCAD only loads code from trusted locations and warns about anything else.
• If AutoCAD shows a security warning about loading an executable file when you open a drawing, choose Do Not Load unless you know exactly what the file is.

Related file extensions

Technical references

Autodesk has never published an official DWG specification. The most complete public technical reference is maintained by the Open Design Alliance, a nonprofit consortium that reverse-engineers the format for interoperability.

• Open Design Specification for .dwg files — Open Design Alliance — The most detailed public technical reference for the DWG format's internal structure, maintained by the ODA consortium.

Frequently asked questions