How to Use Equations in SolidWorks: Simple Guide

In SolidWorks, you use Equations to link dimensions and parameters by creating formulas that control your model automatically. You open the Equations dialog from the Tools menu, then add or edit equations using dimension names and math operators. This helps keep your design consistent and updates dimensions dynamically.

Syntax

Equations in SolidWorks use dimension names and standard math operators to define relationships. You write them as DimensionName = Expression, where DimensionName is the name of a dimension or parameter, and Expression can include numbers, other dimensions, and math symbols like +, -, *, /.

For example, D1@Sketch1 = D2@Sketch1 * 2 means the dimension named D1 in Sketch1 is twice the value of D2 in the same sketch.

solidworks equations

D1@Sketch1 = D2@Sketch1 * 2
D3@Sketch1 = 50
D4@Sketch1 = D3@Sketch1 + 10

Example

This example shows how to set one dimension to be double another and a third dimension to be a fixed value plus an offset.

solidworks equations

D1@Sketch1 = D2@Sketch1 * 2
D3@Sketch1 = 50
D4@Sketch1 = D3@Sketch1 + 10

Output

Dimension D1 is twice D2; D3 is 50; D4 is 60 (50 + 10)

Common Pitfalls

• Wrong dimension names: Using incorrect or misspelled dimension names causes errors.
• Circular references: Equations that refer to each other in a loop will not solve.
• Units mismatch: Mixing units without conversion can give wrong results.
• Forgetting to update: After changing equations, always rebuild the model to apply changes.

solidworks equations

Wrong: D1@Sketch1 = D5@Sketch1 * 2  // D5 does not exist
Right: D1@Sketch1 = D2@Sketch1 * 2

Quick Reference

Term	Description
DimensionName	Name of the dimension or parameter to control
Expression	Mathematical formula using numbers and dimension names
Operators	+, -, *, / for addition, subtraction, multiplication, division
@SketchName	Specifies the sketch or feature where the dimension is located
Rebuild	Apply changes by rebuilding the model after editing equations

Key Takeaways

Use the Equations dialog under Tools to create and manage equations.

Write equations as DimensionName = Expression using correct dimension names.

Avoid circular references and check dimension names carefully.

Rebuild your model after editing equations to see changes.

Equations help automate and control your design dimensions dynamically.