SketchUp Circle by Diameter plugin (Draw Circles Without Thinking in Radius)

Circle by Diameter for SketchUp (A Small Tool I Built to Remove Radius Friction)

SketchUp’s native Circle tool works only with radius. In real projects, almost everything is defined by diameter.

Pipes, holes, bolts, mechanical parts, architectural drawings — they are all dimensioned as Ø values. Yet in SketchUp, you constantly have to divide by two, type /2, and mentally switch context.

After doing this for years, I finally decided to fix it properly. 

Draw circles by diameter not radius

The Everyday Problem

If a drawing says “Ø120 mm”, you think 120, not 60. SketchUp, however, asks for radius, so you end up doing small calculations again and again.

It’s not difficult — it’s just annoying. And when you repeat it hundreds of times per project, it adds up.

Draw circles the way it suits you

What I Built

Circle by Diameter is a small free SketchUp extension (compatible with SketchUp 2017 and later) I created to let you draw circles using the diameter edge instead of a center + radius.

• Enter the number of segments first (same behavior as the native Circle tool)
• Click to define the first diameter point
• Drag or type the diameter value directly (any unit)
  
• The circle is created using that diameter — no division, no mental math

The tool works on:

• Faces (including tilted faces)
• World axes (red / green / blue)
• Construction planes and inferred directions

It behaves like SketchUp’s native Circle tool, but thinks in diameter instead of radius.

Sketchup drawing circle by diameter

Using It Alongside the Native Circle Tool

SketchUp’s default shortcut for the Circle tool is C. The letter D is unassigned by default.

I recommend using both tools together:

1. Keep the native Circle tool on C (radius-based)
2. Assign D to Circle by Diameter

This gives you instant access to both ways of working:

• C → radius-based circle (native SketchUp)
• D → diameter-based circle (this extension)

No menus, no toggles — just muscle memory.

Circle by diameter assign shortcut for easy access

Who This Tool Is For

I built this extension primarily for users who work with real-world dimensions, such as:

• Architects
• Engineers
• Makers, CNC and fabrication workflows

If you are perfectly happy typing /2 every time, you probably don’t need this tool. This is a small helper designed to remove friction, not to replace SketchUp’s native tools.

Draw circle by diameter the easy way

How to use Sketchup Circle By Diameter 

1. Open SketchUp and activate the extension via **Draw → SketchUp Circle By Diameter** or via the shortcut `D`. 
   
2. Enter the number of segments (e.g., 12) and press Enter. 
   
3. Click to define the first edge point of the circle, then drag or type the diameter value and press Enter. 
   
4. Confirm that the circle is drawn with the correct diameter, locked to faces or axes, and behaves like the native Circle tool. 

Why I’m Releasing It for Free

This is a lightweight utility extension. I’m sharing it for free on the SketchUp Extension Warehouse because it solves a very specific annoyance and doesn’t need to be a paid product.

It may later evolve into a more advanced drafting tool, or become part of a larger helper set — or it may remain exactly what it is now.

Either way, it does one thing, and it does it cleanly.

If you naturally think in diameter instead of radius, this tool should feel immediately familiar.