Two emails, five minutes apart, about the same drawing. The laser cutter: "please supply as DXF." The customer: "could you include the DWG?" Meanwhile the new colleague wonders out loud whether that is not simply the same file with a different extension. Almost. And that "almost" is exactly where the trouble starts.
The difference between DWG and DXF is technically small and practically large: it decides who can read your file, what gets lost along the way and how much back-and-forth it takes before the recipient can get to work. From Inventor, a toolbox like Thundercad lets you deliver both formats directly, but you still need to know which format to pick when.
So in this article: what the two formats are, who asks for which one and why, and the two pitfalls (versions and scale) that sooner or later trip up almost every delivery.
Same family, different job
DWG is the working file of AutoCAD: a binary format holding the complete drawing database, from model space and layouts to layers, blocks, text and dimension styles. Open a DWG in AutoCAD and you can carry on working in it as if it had been created right there.
DXF, in full drawing exchange format, was designed to move drawing data between different packages. Its structure is openly documented and the file is readable as plain text. That is why virtually every CAD, CAM and nesting package can import it, including software that has nothing to do with AutoCAD. In terms of content, both formats can hold largely the same drawing; the real difference lies in who has to open the file.
The rule of thumb: DWG is for people who want to keep working on the drawing in AutoCAD or a related package, DXF is for software that only needs to read the geometry.
Who asks for what, and why
| Recipient | Usually asks for | Why |
|---|---|---|
| Customer or engineering firm using AutoCAD | DWG | Wants to work on, with layers, blocks and layouts intact |
| Laser or waterjet cutting shop | DXF | Nesting software reads the 2D contours directly |
| Machining or milling shop | DXF alongside STEP | 2D operations from DXF, the 3D shape from STEP |
| End customer for a plant layout | DWG | Drops your machine as a whole into the floor plan |
The best-known DXF application is sheet metal: the flat pattern of a folded plate goes to the cutting machine as a DXF. How to make that flat pattern genuinely cut-ready, with the right contours and no clutter around them, is a story of its own; you can read it in from flat pattern to a DXF your laser cutter loves.
Is your recipient not in the table? Asking costs one email and beats guessing a format. And if the answer is "either is fine", keep it simple: DXF for machines, DWG for people.
Pitfall one: the version
Both formats exist in multiple versions, and a newer version will not open in software that only knows older ones. The result is rarely a tidy message: the file "is not valid", opens empty, or the import silently does nothing. The recipient concludes your file is broken, you see nothing wrong on your side, and the searching begins.
The fix is unexciting but effective: ask which version the recipient can read, and when in doubt deliver a notch too old rather than too new. Almost any package reads an older version; the other way round is where it fails. The controllers of older cutting machines in particular are picky and sometimes want one specific, older DXF dialect.
Pitfall two: scale, units and what the machine sees
The second pitfall lives inside the file. A drawing is a border with views at scale; a cutting machine wants nothing but the contour, at full size. Send the complete drawing to the laser cutter as a DXF and they first have to strip out the border, the dimensions and the text, then hope the scale is right. Every action on their side is a chance for an error you will never get to see.
Units are the second sneaky one. A plate of 250 by 400 millimeters interpreted as inches stands out immediately; a small detail off by a factor sometimes only shows after cutting. And then there is the geometry itself: some controllers can only handle lines and arcs, so splines get rejected or chopped up. Stick to four rules:
- Deliver cutting contours 1:1, in millimeters, with no scale factor inside the file.
- Keep the border, title block and dimensions out of files that go to a machine.
- Check that arcs stayed arcs and were not chopped into hundreds of tiny line segments.
- State the unit explicitly in your email or file name, so a wrong interpretation stands out immediately.
Every recipient with their own format and version: that homework is worth doing once, not at every export. With Thundercad you export DWG and DXF straight from Inventor, the same way every time.
Try 30 days freeBoth formats out of Inventor, no detours
Inventor is not AutoCAD, but your drawing sheets can leave the building as DWG or DXF just fine. With Export DWG (AutoCAD) you save the active drawing as a DWG that opens for the recipient the way you intended it; with Export DXF you turn that same drawing into a DXF for cutting and nesting software in a few clicks. Which version comes out is set in the export configuration: set it up once according to your agreement list and then leave it alone.
For a single drawing that is all you need. When a complete order goes out, with dozens of sheets in several formats at once, exporting one by one still turns into drudgery; that is when Batch Publish converts drawings in bulk to PDF, DWG, DXF and STEP. And what else belongs in such a delivery besides DWG and DXF, from PDF to the bill of materials, is covered in the complete production package.
Frequently asked questions
Is a DXF always 2D?
No, the format can hold 3D data as well. But in day-to-day outsourcing, "a DXF" almost always means the flat 2D variant for cutting and nesting; whoever needs the 3D shape asks for STEP. When in doubt, ask what the recipient is going to do with the file.
Which version do I deliver if I cannot ask?
Pick a comfortably older version. Almost every package and almost every machine controller reads old versions; the risk is nearly always in delivering too new. As soon as you do have contact, record the preferred version in your agreement list and the guessing is over.
Can I create DWG and DXF for a whole order in one go?
Yes, that is what Batch Publish is for: you select the drawings and get the formats you want for each of them, in a single run. If you want to see how much export work that saves, you can try Thundercad free for 30 days.
