Explainer · dwg vs dgn
DWG vs DGN: AutoCAD and MicroStation
By Sumana Kumar · Published 24 Feb 2022 · Updated 29 Aug 2024
Most of the CAD world runs on AutoCAD and its DWG files, but a large and important slice — especially in civil engineering, transport, infrastructure and government work — runs on Bentley MicroStation and its DGN format instead. If you work across those sectors, sooner or later a DGN lands on your desk, and you need to know what it is and how to deal with it. DGN and DWG are the two great rival CAD formats, and the differences between them are real but bridgeable.
This page explains what a DGN file is, how MicroStation's approach differs from AutoCAD's, where each format dominates, and the practical routes for converting and exchanging between them. The free blocks on this site are DWG, and DGN-based users can bring them across too — here's how the two worlds connect.
What a DGN file is
DGN (short for "design") is the native CAD file format of MicroStation, the flagship CAD platform from Bentley Systems. Like DWG, it's a rich binary format that stores a full design — geometry, levels (MicroStation's equivalent of layers), cells (its equivalent of blocks), text, dimensions and references. It's a mature, capable format used heavily in large infrastructure and engineering projects.
There have been two main generations: the older DGN V7 format from the earlier MicroStation versions, and the current DGN V8 format introduced with MicroStation V8, which is what you'll mostly encounter today. V8 lifted many of the older limits and improved interoperability with DWG. If someone sends you a .dgn, it's a MicroStation design file, the DGN-world counterpart to a DWG.
How MicroStation's model differs from AutoCAD's
The two platforms share a lot conceptually — both are precision CAD systems for 2D and 3D — but they use different terminology and some different underlying ideas. AutoCAD organises geometry on layers; MicroStation uses levels. AutoCAD reuses geometry through blocks; MicroStation uses cells. AutoCAD has model space and paper-space layouts; MicroStation has design models and sheet models.
There are deeper structural differences too. MicroStation historically supported very high coordinate precision and a strong reference-file (xref-like) workflow that's central to how big infrastructure projects are organised. Neither system is simply "better" — they're parallel ecosystems with their own conventions. The practical upshot is that a DGN and a DWG hold equivalent kinds of information using different names and structures, which is exactly why translating between them takes a bit of care.
Where each format dominates
The split tends to follow industry. AutoCAD and DWG dominate architecture, building services, interiors, mechanical drafting and the broad general-CAD market — and DWG is the de facto exchange format across most of that world. It's also the format of the blocks and libraries you'll find online, including this one.
DGN and MicroStation are strongest in civil, transport and infrastructure engineering, and in many government and utility organisations — roads, rail, bridges, water and large public-sector projects often run on Bentley software, partly for historical reasons and partly because of MicroStation's strengths in very large, coordinate-precise, reference-heavy projects. If you're in one of those sectors, you'll meet DGN; if you're in building design, you'll mostly meet DWG. Plenty of professionals straddle both.
Opening a DGN in AutoCAD
The good news is that AutoCAD and MicroStation have grown steadily more interoperable, so you're not stuck if you receive the "wrong" format. AutoCAD can import and work with DGN files: the DGNIMPORT command brings a DGN's geometry into a DWG, mapping levels to layers and cells to blocks as best it can. You can also attach a DGN as an underlay (DGNATTACH) to reference it without converting, which is handy when you just need to draw against someone's DGN.
MicroStation, for its part, can open and save DWG files directly — it reads DWG natively, so a MicroStation user can often work with your DWG without converting at all. This two-way native-ish support is relatively recent in CAD history; older workflows leaned much more heavily on dedicated translation, and some of that still applies for complex files.
Converting between DWG and DGN
When you need a genuine conversion rather than an underlay, you have several routes. Within AutoCAD, DGNIMPORT (DGN to DWG) and DGNEXPORT (DWG to DGN) handle the translation, with settings that control how levels/layers and cells/blocks map across. MicroStation can likewise open a DWG and save as DGN, or open a DGN and save as DWG.
As with any cross-platform translation, expect some imperfection on complex drawings — level/layer mapping, linestyles, fonts and certain custom objects don't always survive a round trip cleanly, so it pays to check the result rather than assume it's identical. For simple 2D content the translation is usually clean. Third-party and online converters exist too, but the built-in import/export tools in both platforms are the most reliable starting point for most files.
Using DWG blocks in a DGN workflow
If you work in MicroStation but want to use the free DWG blocks from this site, you have two easy paths. The simplest is to take advantage of MicroStation's native DWG support: open or reference the DWG directly, and MicroStation reads the block as a cell-like element you can place into your design. For a quick one-off, that's all you need.
Alternatively, convert the DWG to DGN (open it in MicroStation and save as DGN, or import it) so the symbol becomes a native cell in your library, sitting alongside your other MicroStation content. Because these blocks are clean 2D geometry — doors, windows, symbols — they translate across the DWG/DGN boundary without trouble. So the DWG/DGN divide is no barrier: whichever platform you're on, the same free block library is usable, it's just a question of which import route fits your workflow.
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Questions
Frequently asked
What is a DGN file?+
DGN (short for "design") is the native CAD format of Bentley MicroStation, the main rival to AutoCAD. Like DWG, it's a rich binary format storing geometry, levels (its term for layers), cells (its term for blocks), text and dimensions.
Can I open a DGN file in AutoCAD?+
Yes. AutoCAD can import a DGN with the DGNIMPORT command, mapping its levels to layers and cells to blocks, or attach it as an underlay with DGNATTACH to reference it without converting.
How do I convert a DGN to a DWG?+
Use AutoCAD's DGNIMPORT to bring a DGN into a DWG, or open the DGN in MicroStation and save it as DWG. For complex drawings, check the result — level/layer mapping, fonts and custom objects don't always translate perfectly.
Can I use DWG blocks in MicroStation?+
Yes. MicroStation reads DWG natively, so you can open or reference a DWG block directly, or convert it to a DGN cell for your library. The clean 2D blocks here translate across the DWG/DGN boundary without trouble.
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