How To Change Measurement Units In SolidWorks
Changing measurement units in SolidWorks requires updating the active document settings, template files, and drafting standards to ensure dimensional consistency across parts, assemblies, and drawings. Mastery of unit systems—such as Millimeter-Gram-Second (MGS) or Inch-Pound-Second (IPS)—prevents costly manufacturing errors and guarantees compliance with ISO, ANSI, or DIN drafting regulations.
Pre-Procedure Planning for SolidWorks Unit Management
Before modifying unit configurations, understanding the hierarchy of parametric dimensions within SolidWorks is vital. A common pitfall is changing units only for the active session without updating default templates, which results in the software reverting to older configurations on the next part creation.
- Essential gear/tools/materials: SolidWorks 2020 or newer, active part/assembly/drawing file (.sldprt, .sldasm, .slddrw), administrative access to modify file templates.
- Mandatory prerequisite knowledge/standards: Familiarity with the SolidWorks FeatureManager Design Tree, understanding of dual-dimensioning practices, and knowledge of ISO/ANSI geometric dimensioning and tolerancing (GD&T) standards.
- Estimated duration benchmarks: 2 to 5 minutes for single file adjustments; 15 minutes for comprehensive template and drafting standard updates.
Step-by-Step Guide to Modifying SolidWorks Units
Step 1: Locate and Access the Document Properties Menu
Open your SolidWorks model, assembly, or drawing. Navigate to the top menu bar, click on Tools, select Options from the dropdown menu, and click on the Document Properties tab. Alternatively, you can use the status bar shortcut located at the bottom-right corner of the SolidWorks interface, which displays the current active unit system.
Pro-Tip: Utilizing the status bar shortcut is the fastest method for toggling between preset unit systems during active modeling sessions without navigating through the main options dialog.
Step 2: Select the Desired Unit System
Within the Document Properties window, click on the Units category on the left-hand pane. You will be presented with a list of standard unit systems, including Angstrom-Gram-Second (AGS), Nanometer-Gram-Second (NGS), Micrometer-Gram-Second (UGS), Millimeter-Gram-Second (MGS), Centimeter-Gram-Second (CGS), Meter-Kilogram-Second (MKS), and Inch-Pound-Second (IPS). Select your required system from this list.
Step 3: Customize Unit Parameters and Decimal Precision
Beneath the primary system selection, locate the Unit decimals section to fine-tune your drafting precision. Specify the decimal place or fractional display for lengths, angles, mass, and volume. For high-precision aerospace or medical components, adjust the length unit from two decimal places (e.g., 0.01 mm) to four or five decimal places (e.g., 0.0001 mm). Ensure that snap increments align with your chosen precision to avoid geometric rounding errors during sketch creation.
Warning: Changing unit precision affects the visual display of dimensions rather than the underlying parametric mathematical model. However, insufficient decimal settings can hide minor geometric interferences in complex assemblies.
Step 4: Save Changes as Default Templates for Future Projects
To ensure that all future parts, assemblies, and drawings open in your preferred unit system automatically, save your current settings as a template. Go to File and select Save As. In the dialog box, change the "Save as type" dropdown to *Part Templates (.prt; *.sldprt)**, *Assembly Templates (.asm; *.sldasm)**, or *Drawing Templates (.drw; *.slddrw)**. Navigate to your designated company template folder, overwrite the existing standard template or create a new one, and verify that SolidWorks references this folder under Tools > Options > System Options > File Locations > Document Templates.
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SolidWorks Unit Systems and Engineering Specifications
| Unit System | Length Standard | Mass Standard | Time Standard | Temperature | Common Industry Application |
|---|---|---|---|---|---|
| IPS | Inch (in) | Pound (lb) | Second (s) | Fahrenheit (deg F) | US Consumer Goods, Automotive, Heavy Machinery |
| MGS | Millimeter (mm) | Gram (g) | Second (s) | Celsius (deg C) | Precision Engineering, Global ISO Manufacturing, Medical |
| CGS | Centimeter (cm) | Gram (g) | Second (s) | Celsius (deg C) | Scientific Research, Physics Simulations, Optics |
| MKS | Meter (m) | Kilogram (kg) | Second (s) | Kelvin (K) | Large-Scale Civil Engineering, Structural Analysis |
Troubleshooting Unit Conversion Inconsistencies
Symptom: Parts appear microscopic or excessively large when inserted into an assembly.
- Root Cause: The part file was created in Millimeters (MGS) while the assembly file is configured to Inches (IPS), or vice versa, causing a 25.4x scaling discrepancy.
- Actionable Fix: Open the individual part file, change the document units to match the assembly using the Document Properties menu, rebuild the model using Ctrl + Q, save, and re-insert into the assembly.
Symptom: Dimension text displays dual units (e.g., millimeters and inches) unexpectedly on drawings.
- Root Cause: The drawing template has dual-dimension display enabled within the drafting standards settings.
- Actionable Fix: Go to Tools > Options > Document Properties > Dimensions, locate the dual dimension display options, and uncheck the setting or modify the tolerance and precision rules to match drawing requirements.
Symptom: Mass properties calculations output incorrect weight and center of gravity data.
- Root Cause: The density of the assigned material was defined using incompatible volumetric units (e.g., kg/m3 applied to an IPS model).
- Actionable Fix: Re-apply the material via the FeatureManager Design Tree, verify that the material density matches your active unit system, and re-calculate mass properties under the Evaluate tab.
Frequently Asked Questions
How do I change units in SolidWorks drawings without affecting the 3D model?
SolidWorks drawing files maintain independent unit settings from their parent part or assembly files. Open the drawing, navigate to Tools > Options > Document Properties > Units, and adjust the system or decimal precision. This changes the displayed dimensions on the drawing sheet without altering the underlying geometry of the 3D part file.
Can I set different units for individual dimensions instead of the whole file?
Yes, you can override global document units for specific dimensions without changing the entire model. Click on the target dimension in your sketch or drawing, navigate to the Dimension PropertyManager on the left side of the screen, scroll down to the primary units section, and uncheck "Use document units" to manually specify a custom unit and precision.
Why do my Mass Properties calculations change when I switch unit systems?
SolidWorks automatically recalculates mass properties based on the active unit system, converting units seamlessly from the underlying database. If your calculated mass appears incorrect after a switch, verify that the material density was assigned using the correct unit scale or manually update the material properties in the material editor.
How do I make my custom unit settings permanent for all new parts?
To make your unit settings permanent, configure a part, assembly, or drawing with your preferred units, then save the file as a template via File > Save As selecting the appropriate template extension. Point your SolidWorks file locations to this template directory in Tools > Options > System Options > File Locations so every new session initializes with your standards.
Optimize Your CAD Workflow Today
Standardizing your SolidWorks measurement units eliminates costly manufacturing discrepancies and accelerates design review cycles across global engineering teams. Implement these unit management protocols into your custom templates today to streamline your mechanical design process.
