Circle not smooth because it is aproximated by line segments

Is there a way to increase the number of line segments used to approximate a circle in order to give it a smoother appearance?

You can learn more about the Measurements Toolbar (formerly Value Control Box VCB) reading these articles:

Measurements Toolbar — SketchUp Help

Measurements Toolbar — Quick Reference List — SketchUp Help


Geo, thanks for the rapid response. The video that you provided shows how to change the number of sides for a particular circle. That setting persists for the session, but reverts to the default of 24 when I start a new session. Is there a way to change this default value?

I was unable to follow the links that you provided for the two articles.

You can also adjust it in the Entity Info dialog if you select the circle segment:

No, it always resets to the default.
It would be nice if the number of sides setting for circles and arcs would stick instead of revert.
It’s a feature that has been requested in the past.

Try them once more. I copied/pasted them again and they work here.


I just installed sketchup and am quite confused about this issue.
Why are circles not just plain round?
And are there bezier curves anywhere?

Maybe someone can clear that up for me. Would me much appreciated! :slight_smile:

Hi Nico, hi folks.

As with many CAD programs, circles are approximated by line segments.

You can change that to whatever number that suits you, up to a limit of 9999 segments.

Keep in mind that using too many segments will increase the number of geometries in your model.

After some use, you will discover that the default 24 is not that bad. Try extruding a cylinder from a circle using the Push/Pull Tool. You will see that the facets that compose the cylinder are smoothed and that the result is not that bad.

Experiment with more segments to find the compromise that will satisfy you.

Try also experimenting with the default 12 segments for arcs. Try more segments to see what suits you. You will discover that different situations may call for different numbers of segments for arcs as well as for circles.

For bezier curves, there are plugins for that.

Just ideas.


I noticed this info box for a curve I have drawn, however, when I type anything in to that box, it’s ignored.
What am I missing here?


When you select the Circle command (or type “C”), you can choose a number value. In the bottom left there will be a dialog box that pops up, with the default 12 sides showing. Type in 24 or 48 (or whatever you want) and it will replace the default. Same thing with an arc.

What you may be missing is that you don’t click in the measurements box for this kind of input, you just let go of the mouse, type your value, and hit enter. Also, you type 48s, not just 48.

I never type an “s” after the number. Just the number and enter.

Sorry, I should have quoted,

This is what I get:

Can you tell me why Segments is grayed out here? Can I only change the number of segments when I am creating an object? I can change the radius, with ugly results, but can’t seem to change the segments.


That’s because it is one edge of the curved surface of that part. SketchUp wouldn’t know what to do with the opposite arced edge or how to fix up the surface when the number of segments in the opposite edges became inconsistent.

You can change the number of sides if the arc is not part of a 3D shape and it is called an Arc in the Entity Info window. The same applies to circles and polygons.

This is one of the reasons you need to be thinking a few steps ahead when you’re modeling. Don’t let the model get ahead of you.

So, it has to be a decision made when modeling and can’t be changed later? Some other CAD programs allow for changes later.

I know I could re-build that section, but it’s not convenient at all. My boss just wanted a smooth curve in a 2D drawing to send to the Shop Bot for cutting pieces. How is that normally done? Surely re-drawing it in Adobe Illustrator is not the best way. That’s terribly redundant work.

Does Layout make this possible? I’ve noticed that what I import from SketchUp to Layout becomes an raster image, no longer vector shapes. Is it possible to import vectors from SketchUp?


I realized that later, and of course I tried to select both curves and change them both, but that’s not allowed.

My point is that it is a good idea to anticipate how the model will be used and the sort of detail you’ll need from it and model accordingly.

No. It’s probably not convenient but that’s the way it is. No one said anything about redrawing it in Illustrator. Normally the group or component would get edited as needed. It’s much more convenient to draw the model to suit the way it’ll be used or at least to model it so it is easy to modify in you have to do so.

LayOut won’t give you a 3D model if you need that. You can create 2D drawings in LayOut. If the curves come from SketchUp, they will be approximated with line segments just as the SketchUp model shows.

As for the Raster render, that’s the way the viewports first render but you can change to Vector render if you wish.

If this is of any help at all now/-not too late,…
you might try this.
(get rid of the locking geometry, change the two arcs and quickly repair)

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My boss did. He told me that what I gave him from SketchUp was unusable for his purpose, so he would just redraw it in Illustrator, which meant that my work was of no help whatsoever to him.

He is using a Shop Bot CNC router to cut pieces out of MDF or plywood, or sheets of some other material. For this, he needs me to provide him with 2D vector views of the 3D model. I know this is a common practice. This is something people do every day. I’m trying to learn how to do it.

That would be helpful. How is that done? I could find no setting for this.

So, should I be drawing flat profiles in Layout first, and somehow importing those into SketchUp for modeling?



I’m just not sure how “a little push/pull” would be done in that situation, but I will experiment.