Is it possible to have two different units (inches and mm) in the same sketch in SolidWorks?

Short Answer

Yes — in SolidWorks, it is possible to use inches and mm in the same sketch by entering dimension values with unit suffixes while working in a single document unit system. The most common professional method is editing sketch dimensions through Smart Dimension and typing values like 25mm or 1in. However, the sketch itself still stores one active document unit standard.

What You Need to Know Before

Warning: Mixing inches and mm in the same sketch can easily create wrong-sized geometry if you assume the document units automatically change per dimension. A common failure is typing bare numbers without unit suffixes, which makes SolidWorks interpret them only in the current part or sketch document units.

How to Do It

• Command: Smart Dimension

• Shortcut: S (Shortcut Bar, if configured) / no default single-key shortcut

• Quick Steps:

  1. Start or edit a sketch, then go to the Sketch toolbar or CommandManager and click Smart Dimension.
  2. Select the sketch entity to dimension, then place the dimension in the graphics area.
  3. In the Modify box, type the value with an explicit unit suffix such as 50mm or 2in, then confirm. SolidWorks converts it using the current document unit settings.
  4. If needed, check document units under Tools > Options > Document Properties > Units to verify the base unit format used by the file.

Variables & Settings

• Key Setting: Document Properties > Units

• Expert Setting: This controls the file’s main unit system, precision, and display format. Even when you enter mixed-unit values manually, SolidWorks converts and stores them according to the active document units, so displayed values may not remain in the originally typed unit.

Why it Fails

• Cause 1 (Geometry): The sketch becomes incorrectly sized because dimensions were entered without mm or in, so SolidWorks applies only the active document unit.

• Cause 2 (layers/Locks): Linked equations, design tables, or locked dimension relationships may override manually entered mixed-unit values.

• Cause 3 (Command/Logic): SolidWorks does not run a sketch with independent per-dimension native unit systems; it only allows unit conversion on input while the document keeps one governing unit format.

Quick Fix & Best Practice

• Quick Fix: Edit the affected dimensions with Smart Dimension and re-enter each value using explicit unit suffixes like mm or in, then verify the file unit setting in Document Properties > Units.

• Manager’s Verdict: Use one document unit system for the entire part and only use mixed-unit input when importing vendor dimensions or legacy data. For production models, standardizing units reduces mistakes, equation issues, and drawing confusion.

FAQ

Can SolidWorks show some sketch dimensions in mm and others in inches at the same time?
Not as a true native mixed sketch standard; input can be mixed, but the document still uses one main unit system.

Can I type 3in in a metric solidworks part?
Yes, SolidWorks converts it automatically to the active document units.

Should I switch document units instead of mixing inputs?
Usually yes, unless you are working from reference dimensions supplied in different unit systems.

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