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How do I change the unit system in Revit?

Published in Revit Units 4 mins read

To change the unit system in Revit, you primarily use the Project Units settings, accessible via the Manage tab.

Step-by-Step Guide to Changing Units in Revit

Changing the unit system in Revit is essential for ensuring your project conforms to regional standards or specific project requirements (like using millimeters instead of inches, or meters instead of feet). The process involves accessing the project settings and modifying the units for different disciplines and measurements.

Here are the steps to change the units based on the standard Revit workflow:

  1. Access Project Settings: Navigate to the Manage tab on the Revit ribbon. Within the Settings panel, click the Project Units button.
    • Reference Step 1: Click Manage tab Settings panel.
  2. Open Project Units Dialog: This action opens the Project Units dialog box, which lists various unit types organized by discipline.
  3. Select Discipline: In the Project Units dialog, choose the discipline whose units you want to change. Disciplines typically include Common, Architectural, Structural, HVAC, Electrical, and Piping.
    • Reference Step 2: In the Project Units dialog, select the discipline.
  4. Modify Unit Format: For the specific unit type you wish to modify (e.g., Length, Area, Volume), click on the value displayed in the Format column. This action opens the Format dialog for that unit.
    • Reference Step 3: Select the value in the Format column to change the display value for that unit type.
  5. Specify Units and Rounding: In the Format dialog, you can now:
    • Select the desired Units from the dropdown menu (e.g., millimeters, meters, feet, inches, square meters).
      • Reference Step 4: Specify Units, if necessary.
    • Choose the Rounding precision from the dropdown (e.g., 0 decimal places, 2 decimal places, or a specific fraction).
      • Reference Step 5: For Rounding, select an appropriate value.
    • You can also configure the Unit Symbol, Suppress Trailing Zeros, Suppress Leading Zeros (for fractional units), and Suppress Spaces settings as needed.
  6. Confirm Changes: Click OK in the Format dialog to apply the changes for that specific unit type. Repeat steps 3-5 for any other units or disciplines you need to modify.
  7. Finalize Settings: Click OK in the Project Units dialog to close it and apply all the changes to your project.

Understanding Different Unit Types

Revit organizes units not just by discipline but also by the type of measurement they represent. Common unit types you'll encounter and likely need to adjust include:

  • Length: Used for walls, beams, dimensions, etc. (e.g., mm, m, feet, inches).
  • Area: Used for rooms, surfaces, etc. (e.g., m², ft²).
  • Volume: Used for concrete, spaces, etc. (e.g., m³, ft³).
  • Angle: Used for slopes, rotations, etc. (e.g., degrees, radians).
  • Slope: Used for roofs, pipes, etc. (e.g., rise/12", percentage, degrees).
  • Currency: For cost estimation features.

Each discipline will have relevant unit types listed in the Project Units dialog. For instance, MEP disciplines (HVAC, Electrical, Piping) have specific units for flow rates, pressures, temperatures, power, voltage, etc., which you can adjust similarly.

Practical Considerations

  • Templates: Project Unit settings are saved with the Revit project file. If you want to start new projects with your preferred unit system, configure the units in your project template (.RVT) file.
  • Existing Elements: Changing units affects how dimensions and tags display values for existing elements. Revit automatically converts the underlying numerical values to the new unit display.
  • Linking Files: When linking other Revit models or CAD files, their units are typically handled during the linking process, often requiring you to specify units or rely on auto-detection.

By following these steps, you can effectively change the unit system within your Revit project to suit your needs.

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