How to change units from inches to millimeters in BricsCAD?

ByCADbrief Staff

Short Answer

To change units from inches to millimeters in BricsCAD, use the -DWGUNITS command and choose millimeters when prompted. This is the fastest professional method because it can also scale existing geometry to match the new unit setting. Limitation: if blocks or xrefs were inserted with wrong units earlier, they may still need manual correction.

What You Need to Know Before

Warning: Changing drawing units does not always fix everything automatically. If the file was drafted in inches but inserted into other drawings, switching to millimeters can create scale errors in blocks, xrefs, dimensions, or layouts if insertion units were already mismatched.

How to Change Units from Inches to Millimeters in BricsCAD

  • Command: -DWGUNITS

  • Shortcut: No default shortcut

  • Quick Steps:

    1. Type -DWGUNITS in the command line and press Enter.
    2. At the unit prompt, choose Millimeters.
    3. When prompted, confirm Yes to scale objects in the current drawing if the geometry was originally drawn in inches.

Variables & Settings

  • System Variable: INSUNITS (Default: 0)

  • Expert Setting: INSUNITS controls the insertion scale used when blocks or xrefs are brought into the drawing. Set it to 4 for millimeters so future inserts scale correctly. If this remains set incorrectly, the drawing may still behave like an inch-based file during insert operations.

Why it Fails

  • Cause 1 (Geometry): The drawing units were changed, but existing geometry was not scaled from inches to millimeters, leaving objects at the wrong physical size.

  • Cause 2 (layers/Locks): Objects inside locked layers, blocks, or attached references may not update as expected during cleanup, making the file appear partially converted.

  • Cause 3 (Command/Logic): Users often change INSUNITS only, which updates insertion behavior but does not rescale existing drawing geometry.

Quick Fix & Best Practice

  • Quick Fix: Run -DWGUNITS, set the drawing to millimeters, and accept the scaling option. Then check INSUNITS and set it to 4.
  • Manager’s Verdict: Use -DWGUNITS when converting a real inch-based drawing to millimeters. If the file is already correctly sized and only insertion behavior is wrong, change INSUNITS instead of rescaling the geometry.

FAQ

How do I check the current units in BricsCAD?

Run INSUNITS or use -DWGUNITS to review the current drawing unit setting.

Does changing INSUNITS convert the drawing to millimeters?

No, INSUNITS only affects insertion scaling for blocks and xrefs.

Will dimensions update automatically after unit conversion?

Usually the geometry scales, but dimension styles and annotation settings should still be checked manually.

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