How to Use Global Variables in SolidWorks: Simple Guide

In SolidWorks, you create Global Variables via the Equations dialog to define values that can control multiple dimensions or features. These variables help keep your model consistent and easy to update by referencing them in dimension fields using =VariableName syntax.

Syntax

Global variables in SolidWorks are created and used through the Equations dialog box. You define a variable name and assign it a value or formula. Then, you reference this variable in dimension fields by typing =VariableName.

• Variable Name: A custom name you assign (e.g., Length).
• Value/Equation: The numeric value or formula assigned to the variable (e.g., 100mm or Width * 2).
• Reference in Dimensions: Use =VariableName in dimension input to link it.

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Global Variable Definition:
Length = 100 mm
Width = 50 mm
Height = Length / 2

Dimension Input Example:
=Length
=Width
=Height

Example

This example shows how to create global variables for length and width, then use them to control a rectangle's dimensions. Changing the variables updates all linked dimensions automatically.

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1. Open SolidWorks and create a new part.
2. Go to <strong>Tools &gt; Equations</strong>.
3. Click <strong>Add</strong> and enter:
   - Name: Length
   - Value: 100 mm
4. Add another variable:
   - Name: Width
   - Value: 50 mm
5. Close the Equations dialog.
6. Create a rectangle sketch.
7. Set the horizontal dimension to <code>=Length</code>.
8. Set the vertical dimension to <code>=Width</code>.
9. Exit the sketch and rebuild the model.
10. To change size, reopen Equations and modify Length or Width values.

Output

The rectangle's horizontal side measures 100 mm and vertical side measures 50 mm. Changing Length to 120 mm updates the horizontal side to 120 mm automatically.

Common Pitfalls

• Variable Naming: Avoid spaces or special characters in variable names; use underscores if needed.
• Case Sensitivity: Variable names are case sensitive; Length and length are different.
• Referencing Variables: Always start dimension input with = to link to a variable; forgetting this treats it as a number.
• Updating Variables: After changing variables, always rebuild the model to see updates.

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Wrong:
Dimension input: Length  (no = sign)

Right:
Dimension input: =Length

Quick Reference

Action	Description	Example
Create Variable	Define a global variable in Equations dialog	Length = 100 mm
Use Variable	Reference variable in dimension input with =	=Length
Edit Variable	Change value in Equations to update model	Length = 120 mm
Avoid Errors	No spaces in names; use = to reference	Width_1, not Width 1
Rebuild Model	Press Rebuild after changes	Ctrl + B or Ctrl + Q

Key Takeaways

Create global variables in the Equations dialog to control multiple dimensions easily.

Reference variables in dimension fields by typing =VariableName to link them.

Use simple, consistent variable names without spaces or special characters.

Always rebuild your model after changing variables to update dimensions.

Global variables help keep your design flexible and easy to modify.