CAD File Formats Explained: DWG, DXF, RVT and IFC
DWG is AutoCAD's native drawing format, DXF is an open exchange version of it, RVT is the native Revit model format, and IFC is the open format for sharing BIM models between different software. Knowing which one to ask for, and which to send, avoids most file problems before drafting starts.
By Fayez 4 min read
DWG: the standard 2D drawing file
DWG is the native file format of AutoCAD and the format most drafting offices use for 2D drawings. It stores geometry, layers, blocks, text styles, dimension styles and layouts. Many other programmes can open it.
- Use it for: plans, sections, elevations, details and anything that will be edited further in AutoCAD.
- Watch for versions: newer AutoCAD versions save files that older versions may not open. If your team uses an older release, say so, and ask for the file to be saved in a format your version can read.
- Watch for references: a drawing may depend on external references (xrefs), images or fonts. Send them with the drawing, or the file will open with missing content.
DXF: an exchange format
DXF (Drawing Exchange Format) was created by Autodesk to move drawings between different CAD programmes. It carries geometry and basic layer information but is less complete than DWG and may lose some advanced features such as certain dynamic blocks.
- Use it for: sending drawings to people who do not use AutoCAD, or to machines such as laser cutters and CNC equipment that read DXF.
- Do not use it for: the main working file when both sides use AutoCAD. DWG keeps more information.
RVT: the Revit model
RVT is the native file format of Autodesk Revit, the most widely used BIM tool. An RVT file is not a drawing. It is a database of building elements, such as walls, floors, doors and pipes, from which plans, sections, schedules and 3D views are produced.
- Use it for: the live BIM model that the project team works in.
- Watch for versions: a Revit file can be opened in the same or a newer version of Revit, but not in an older one. Agree the Revit version at the start of the project.
- Related files: RFA files are Revit families (reusable components) and RTE files are Revit templates. Send your template and families if you want the model to follow your standards.
IFC: sharing models between software
IFC (Industry Foundation Classes) is an open, vendor-neutral format for exchanging BIM data. It lets a model made in one programme be opened in another, and is often specified for coordination between disciplines and for handover.
- Use it for: coordination between teams that use different software, clash detection in a federated model, and delivery when a client asks for an open format.
- Be aware: exporting to IFC is not a perfect copy. Settings affect what is exported, so check the result and agree an export setup if IFC is a required deliverable.
PDF: for review, not for editing
PDF is the usual format for review and issue. It shows exactly what the sheet looks like but cannot be edited like a CAD file. Ask for PDFs of every sheet alongside the native files, so you can check drawings without opening CAD software.
Other formats you may meet
- NWD and NWC: Navisworks files, used for model coordination and clash detection.
- DWF: a lightweight Autodesk format for sharing and markup, now less common.
- Point cloud files (such as RCP, RCS or E57): scan data used as the source for Scan to BIM.
- COBie: a structured spreadsheet format for handing over asset data on some projects.
A quick guide: which format for which job?
- Editing 2D drawings in AutoCAD: DWG.
- Sending a drawing to a machine or another CAD programme: DXF.
- Working on a BIM model in Revit: RVT.
- Sharing a model between different software: IFC.
- Reviewing and issuing sheets: PDF.
What to tell your drafting team
Put these four points in the brief:
- The software and version you use, for example the AutoCAD or Revit release.
- The file formats you want delivered, native and PDF, and whether IFC is needed.
- Your template, layers, families and naming rules.
- All external references, fonts and images that the files depend on.
Our guide on how to brief a CAD drafter covers the full brief. OEG's team works in Revit, AutoCAD and Navisworks, from LOD 100 to 500, inside your templates and standards. See our CAD drafting and BIM teams and BIM modelling and coordination services.
Frequently asked questions
What is the difference between DWG and DXF?
DWG is AutoCAD's native format and holds the full drawing. DXF is an exchange format for moving drawings between programmes or to machines. It is less complete than DWG.
Can an older version of Revit open a newer RVT file?
No. A Revit file opens in the same or a newer version, not an older one. Agree the version before the project starts.
When should I ask for IFC?
Ask for IFC when you need to share a model with teams using different software, or when the client requires an open format for coordination or handover.
Which files should I send to a drafter?
Send the source drawings in their native format, with all external references, fonts and images, plus your template and standards. Include PDFs so the drafter can see how the sheets should look.
To talk about your project, book a consultation.