When working between Revit and Rhino/Grasshopper via Rhino.Inside.Revit, unit conversion is a critical step because Revit and Rhino might be using different unit systems. Users need to be aware of the following:

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Scale Adjustments: If the Rhino model is in millimeters and the Revit project is in feet, objects may need to be scaled to match the correct dimensions.

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Precision Differences: Revit's unit settings are generally optimized for architectural projects, so the tolerance or precision might differ compared to Rhino’s high-resolution modeling environment.

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Model units mismatch warning

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Revit Unit Settings

Rhino Unit Settings

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Precision Differences: Revit's unit settings are generally optimized for architectural projects, so the tolerance or precision might differ compared to Rhino’s high-resolution modeling environment.

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Change unit system and maintain object sizes

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Understanding and aligning units is essential when transferring data between these platforms to ensure accurate and scalable models.

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Aspect Revit Rhino Grasshopper
Unit Type Project-wide unit system (Imperial or Metric). Model-based unit system (Imperial or Metric). Follows Rhino’s unit system. No independent unit setting.
Unit Flexibility Units are set at the project level. Consistent across the model. Units can be changed anytime, scaling the model as needed. Follows Rhino’s units. Numeric values are scaled accordingly.
Precision & Control Architectural or engineering precision with specific rounding. High precision; tolerance and resolution can be set for accuracy. Numeric values follow Rhino’s precision settings.
Use Case Focus Construction documentation and BIM standards. Versatile modeling for architecture, industrial design, etc. Computational design; parametric workflows within Rhino’s units.
Unit Conversion Needs attention when importing/exporting to other software. Automatically scales when units change, ensuring model integrity. Unit handling depends on Rhino’s unit system. Manual scaling can be used.
Project-Level Units Defined within "Project Units" settings. Defined per model in the "Document Properties" settings. Relies on Rhino’s model unit settings.
Handling Real-World Scale Primarily focuses on real-world building dimensions. Can handle both real-world scale and abstract design. Deals with numbers; scale needs to match Rhino's units for accuracy.

Unit Comparison