How to open CAD files

To open a CAD file, first check its extension: DWG and DXF open right on this page in the browser, while DWF, DGN, STEP, STL, RVT, and SKP each need their own reader. Drop a DWG or DXF on the area above and it opens in seconds, read on your device without uploading.

Open a CAD file online in this tab

1. Drag the .dwg or .dxf file onto the drop area above, or click it and choose the file.
2. Wait a moment. The first DWG in a session loads a 9 MB WebAssembly module once; after that, a typical drawing of 1 to 20 MB opens in 1 to 10 seconds on a laptop.
3. Pan with the mouse, zoom with the wheel, and press fit to view if the drawing seems empty.
4. Open the layers panel to show or hide layers, measure between two points, print, or export PDF, PNG, or SVG.

This CAD reader works in Chrome, Edge, Firefox, and Safari on Windows, macOS, Linux, and ChromeOS. Phones and tablets handle small and medium files; large drawings are better on a computer.

Which program opens which CAD file

When a CAD file will not open

Most failures come from three causes. The file is not what its name says: a PDF or a ZIP renamed to .dwg, which happens when email systems or download tools rename attachments. The file is very old: DWG from R12 and earlier opens only partially here. Or the file is very large: DWGs over 60 MB are skipped to protect browser memory.

Check the size first, then try opening the file in a second program. If a ZIP arrives, unzip it and look for the .dwg inside; drawing sets are often sent with fonts and references in one archive. The step-by-step checklist is on DWG file not opening.

Missing fonts, references, and images

A CAD drawing is often more than one file. Text styles point to SHX or TrueType fonts on the author's computer, external references (xrefs) point to other DWGs, and image underlays point to picture files. When you open the drawing on another machine, those links break.

Here, missing fonts are replaced with a substitute so text stays readable, though spacing may shift. Content that lives in an external reference is not part of the file and will not appear. If a plan looks half empty, ask the sender to bind the references into the drawing or to send them as one package with eTransmit.

Open CAD files on a phone or tablet

The viewer runs in Safari on iPhone and iPad and in Chrome on Android, so a DWG or DXF from an email attachment opens without an app. Save the attachment to Files or Downloads, open this page, tap the drop area, and pick the file. Pinch to zoom and drag with one finger to pan.

Phones have less memory than laptops, so small and medium drawings work best. A large DWG may run out of memory and fail to open; if that happens, open it on a computer, export a PDF, and send the PDF to the phone. Mobile options are compared on DWG viewer for iPhone and DWG viewer for Android.

Privacy: what happens to the file

The drawing is read by JavaScript in your browser tab. It is converted and drawn on your device, nothing is sent to a server, and closing the tab removes it. That makes this page suitable for client drawings and files under NDA, where an upload-based online CAD reader would be a problem.

For a broader look at viewing tools, see the CAD viewer page, and what is a CAD file for the formats themselves.

Frequently asked questions