Why dragging the mouse doesn’t work—and what to do instead
If you’re new to SketchUp, one of the first frustrations you may hit is this:
“I created a rectangle… but now I want to change its dimensions. Why is it so hard?”
A user on the SketchUp Forum asked exactly this question, and the thread became a goldmine of practical advice. Let’s break down the proper way to resize rectangles—and why SketchUp behaves the way it does.
Why You Can’t Just “Type Width and Height” on a Rectangle
In SketchUp, once a rectangle is drawn, it becomes raw geometry made of edges and a face. It doesn’t remain a “rectangle object” with editable width and height fields. That’s why you can’t simply select it and enter new dimensions.
SketchUp isn’t parametric (unless you use Dynamic Components or extensions). Instead, you modify shapes using tools like Move, Scale, and Tape Measure.
That said:
Changing a rectangle’s size is simple, once you know the correct workflow.
Method 1: Move an Edge, Then Type the Exact Distance (Fastest Method)
This is the method recommended by several experts in the thread.
Steps:
- Select the Move Tool.
- Click the edge you want to move.
- Start dragging it—just a tiny bit.
- Without clicking again, type the exact distance you want (ex:
200mm). - Press Enter.
Important:
- You DO NOT click in the Measurements Box.
- You DO NOT try to position the mouse precisely.
- Just type the number and SketchUp updates the movement with perfect accuracy.
This is the most common beginner mistake:
People think they must move the mouse the exact amount.
But SketchUp doesn’t work like that.
You start an action with the mouse, and finish it precisely with the keyboard.
Method 2: Use the Tape Measure Tool to Create a Guide, Then Move the Edge
Forum sager slbaumgartner explained this clean trick:
- Activate Tape Measure.
- Measure 200mm from one edge → this creates a guide line.
- Use Move Tool to drag the edge.
- Snap to the guide.
This is perfect when you want a clear visual reference.
Method 3: Use the Scale Tool for Proportional or Non-Proportional Resizing
If you want to resize the entire rectangle:
- Triple-click the rectangle to select all connected geometry.
- Press S for the Scale tool.
- Drag the appropriate handle.
- Type a value:
2(×2 scale)0.5(reduce by half)800mm(absolute size if dragging one axis)
Scale is powerful, but must be used carefully to avoid distorting surrounding geometry.
Method 4: Convert to a Component for Reusable Parametric Editing
If you expect to resize shapes often:
- Select the rectangle.
- Right-click → Make Component.
- Now you can scale it freely without affecting other geometry.
Not true parametric editing, but very practical.
Common Beginner Mistakes (All Covered in the Forum Thread)
❌ Mistake 1: Trying to eyeball the movement with the mouse
You will never land precisely on 200mm by moving the mouse alone.
Use the keyboard every time.
❌ Mistake 2: Clicking inside the Measurements Box
SketchUp ignores mouse clicks there.
Just type.
❌ Mistake 3: Starting to type before moving the mouse
The measurement applies only after starting the move action.
❌ Mistake 4: Forgetting units
If your model is in mm, typing 200 automatically means 200mm.
But typing 200m or 200cm also works.
Example: Resize a rectangle from 403.6 × 1196.7 mm to 200 × 800 mm
To change width:
- Move the left or right edge.
- Start dragging → type
200mm→ Enter.
To change height:
- Move the top or bottom edge.
- Start dragging → type
800mm→ Enter.
Done.
Why This Feels Confusing at First
SketchUp is built around direct modeling.
Other software (Fusion 360, SolidWorks, FreeCAD) uses parametric modeling, where you type dimension values into fields.
SketchUp is different:
- You draw shapes.
- You edit edges and faces directly.
- The Measurements Box is not a form—it’s a real-time command line.
Once you understand that, SketchUp becomes incredibly fast and intuitive.
Final Takeaway
Changing dimensions in SketchUp isn’t hard—it’s just different from traditional CAD.
The secret is: start with the mouse, finish with the keyboard.
Once you get used to it, resizing shapes with perfect accuracy becomes second nature.
