How to Convert MicroStation DGN to AutoCAD DWG (Step-by-Step Guide)

Converting MicroStation (.DGN) files to AutoCAD (.DWG) is standard work in mixed CAD environments. The method you use directly impacts layer structure, units, references (Xrefs), and file performance. This guide covers the workflows that actually hold up in production, including export, import, batch processing, and cleanup.

Method 1: Export from MicroStation (Recommended Workflow)

This is the most reliable method. MicroStation translates its own format more cleanly than AutoCAD does.

Steps

1. Open the .DGN file in MicroStation
2. Go to File > Export > AutoCAD Drawing (.DWG)
3. Click Options before saving

Key Settings

• Level Mapping (Levels → Layers) Map MicroStation Levels to AutoCAD Layers properly → Avoids layer chaos after importPro tip: Save your mapping as a reusable file (.csv or .v7cfg) → eliminates remapping for every project (essential for BIM/CAD managers)
• Fonts Conversion Enable conversion to AutoCAD SHX fonts → prevents missing or unreadable text
• References (Xrefs)
  • Merge → single DWG file (good for delivery)
  • Retain → keeps Xrefs (better for ongoing projects)
• DWG Version (Important) Export to a lower version (e.g., AutoCAD 2018) → ensures maximum compatibility across teams, even if you’re using newer versions like 2024

Units and Scale (Most Common Failure Point)

MicroStation uses Working Units:

• Master Units
• Sub Units

If these don’t align with AutoCAD units, you get scaling errors.

Example:

• 1 meter becomes 1000 meters after import

Always verify:

• Working Units in MicroStation
• Target units in AutoCAD

Notes from Production

• Best method for preserving:
  • Line styles
  • Cells (blocks)
  • Annotations
• Always validate output:
  • scale
  • layers
  • references

Method 2: Import in AutoCAD (DGNIMPORT)

Use this when MicroStation is not available.

Limitation: Only available on AutoCAD Windows, not Mac.

Steps

1. Open a DWG file
2. Run: DGNIMPORT or go to Insert > Import > DGN

Conversion Settings

• Units Check (Critical) Match units to avoid scaling issues (linked to MicroStation Master/Sub Units)
• Enable: Import DGN underlays as block references → allows editing after import

Cleanup Workflow (Mandatory)

After import, run:

• PURGE → removes unused objects
• -PURGE > R (Regapps) → removes hidden DGN application data (major performance gain)
• AUDIT → fixes errors
• OVERKILL → removes duplicate geometry

Reality Check

• Expect:
  • duplicated line styles
  • messy layers
  • heavier files

Batch Conversion (Multiple DGN Files)

For large datasets, use MicroStation’s Batch Process tool.

Steps

1. Open Batch Process
2. Add multiple .DGN files
3. Set output format to DWG
4. Define output folder
5. Run

Use Cases

• Infrastructure projects
• Legacy CAD migration
• Multi-discipline coordination

Handling References (Xrefs)

Your choice here affects usability downstream.

• Merge
  • Single DWG
  • Easier for delivery
  • Harder to update
• Retain
  • Keeps external references
  • Better for collaborative environments

2D vs 3D Conversion

When converting 3D DGN → 2D DWG:

• Set Top View before export

In AutoCAD

• FLATTEN
  • Works in many cases
  • Part of Express Tools
  • Can fail on complex blocks
• FLATSHOT (Recommended alternative)
  • Generates a clean 2D representation from 3D
  • More reliable for complex models

Common Problems and Fixes

Wrong Scale

Cause: Unit mismatch (Master/Sub Units vs AutoCAD units) Fix:

• Verify units before export/import
• Use SCALE (reference option) if needed

Broken or Messy Layers

Cause: No proper level mapping Fix:

• Use saved mapping configuration file
• Align with internal CAD standards

Canadian Standards (BNQ / Hydro-Québec)

If you work in Québec/Canada:

• Respect layer naming standards (BNQ, Hydro-Québec, etc.)
• Map MicroStation Levels accordingly → avoids rework during coordination

Missing Text

Cause: Font mismatch Fix:

• Enforce SHX conversion during export

Heavy / Slow Files

Cause:

• DGN line styles
• duplicate geometry
• hidden Regapps

Fix workflow:

• PURGE
• -PURGE > Regapps
• OVERKILL
• AUDIT

Alternative Tools (When MicroStation Is Not Available)

• Bentley View Viewer only (no DWG export anymore) https://www.bentley.com/software/bentley-view/
• ODA File Converter Useful for format conversion and batch processing https://www.opendesign.com/guestfiles/oda_file_converter

Note

• Bentley View is for visualization only
• For export without a full license:
  • use MicroStation trial
  • or legacy PowerDraft versions

Platform Limitation (Mac Users)

• AutoCAD for Mac does not support DGNIMPORT
• Options:
  • Export from MicroStation
  • Run AutoCAD Windows (Parallels / Boot Camp)

Comparison Table

Professional Workflow Recommendation

Standard workflow in production:

1. Export from MicroStation
2. Use saved mapping configuration
3. Export to AutoCAD 2018 format
4. Clean DWG in AutoCAD:
   • PURGE
   • -PURGE (Regapps)
   • AUDIT
   • OVERKILL
5. Validate:
   • scale
   • layers
   • references

Tools and Utilities

If you’re working on unit conversions, scale validation, or CAD workflows, you can centralize your calculations here: https://www.jecalcule.ca

(Useful for quick checks when dealing with unit mismatches between MicroStation and AutoCAD.)

FAQ

Can AutoCAD open DGN files directly?

Yes, using DGNIMPORT, but only on Windows versions of AutoCAD. Expect cleanup afterward.

What is the best way to convert DGN to DWG?

Export from MicroStation. It gives the most stable result for layers, references, and annotations.

Why is my scale wrong after import?

Because MicroStation Working Units (Master/Sub Units) don’t match AutoCAD units.

Why is my DWG file slow?

Because of:

• unused DGN data
• duplicate geometry
• hidden Regapps

Fix with:

• PURGE
• -PURGE > Regapps
• OVERKILL

Can I convert multiple DGN files at once?

Yes, using Batch Process in MicroStation or tools like ODA File Converter.

Why are my layers disorganized?

Because MicroStation uses Levels, not layers. Without mapping, AutoCAD creates inconsistent structures.

What is better: FLATTEN or FLATSHOT?

• FLATTEN: quick, but unreliable on complex objects
• FLATSHOT: cleaner and more stable for 3D → 2D conversion

Can I export without a MicroStation license?

Not with Bentley View. Use:

• MicroStation trial
• or legacy PowerDraft versions

This workflow reflects what works on real projects. If the mapping, units, and cleanup are handled properly, the conversion becomes predictable and repeatable.