I have the following figure in which I need to make a fillet to each its corners:

enter image description here

Is there some tool to avoid doing this manually? I tried the Effect > Stylize > Round Corners tool but it apply the roundness also to the circles.
I'm using the CS6 version of Adobe Illustrator.

5 Answers 5


The others have given an answer that works by eyeballing and plugin. I will give 2 answers that work by measurement. The other one uses a script the other is manual.

By Script

There is a wonderfully useful script by Hiroyuki Sato, called round any corner, that allows you to do this quickly and painlessly much like CC verisons. Although the gui is a bit more clunky.

enter image description here

By offset

If you have shape that you want to round by say 12 pt radius then you can offset the path by -12 pt and place the center of a circle on the new corner. (you can draw a exact circle by alt clicking on corner of the offset and type in 24pt by 24 pt).

enter image description here

Now while this may not be usefull for round corners en masse its good when you need accurate nonround corners ;)

Also a offshot of this trick is to offset inside then otside by same amount, but this can also adjust the overall shape of noncorners.

  • The offset technique is genius!
    – spiral
    Commented Jan 23, 2018 at 10:25
  • Mr. Sato's plugin is amazing. It's amazing that something that takes 2 seconds in AutoCAD and has been available in that software for decades is so clunky in AI.
    – Bort
    Commented May 20, 2021 at 1:44
  • @Bort well illustratir cs6 is a decade old and rounding in a modern illustrator makes autocad feel clunky
    – joojaa
    Commented May 20, 2021 at 4:05
  • But then illustrator does not do chamfers, extend lines, tangent lines, parabolic chamfers, c2 continious chamfers, tangent snapping etc... But CAD apps dont do what you see is what you get, or even half of the color stuff and autocad has a comfortable decade more time in development. All software sucks in some way compared to some other tool, but are better in other ways.
    – joojaa
    Commented May 20, 2021 at 4:12

There's no easy way to do this nativley in Illustrator CS6. (In the last couple of CC editions Adobe implemented a tool called Live corners which does it)

If you just used the Rounded Corner effect, it warps the circle (see below)

You have to do a bit of prep first:

Add in a line (dashed in my case) in a locked background layer (to align both my anchor points evenly)

Then place 2 anchor points there (one on each side), and only then can you use the Effects → Rounded Corners

The problem with first doing rounded corners effect, is that it causes the circle to get warped (because there aren't any anchor points, if you add them in, it stops the rounding at that anchor point)

enter image description here

Notice, that I did not add in anchor points to the bottom part, and it got warped I've added a new gif

Update: in my image it seems as though it is warping the path. here are the outcomes (after rounding corner effect):

enter image description here

Overlayed at 30% (after that anchor point, none of the rest of the path is effected):

enter image description here

For a much easier and simpler method, I would recommend a great plug-in by Astute Graphics* called Vectorscribe.

It is very simple and easy to use. (It isn't free, however they offer a 14 day free trial)

It also has some other tools included in vectorscribe, like measurements and path cleanup

Vectorscribe in action:

enter image description here

*I'm not affiliated with Astute Graphics

  • 1
    I would avoid just posting "use plugin X" answers. Our goal here is to educate with techniques. Commented Jan 22, 2018 at 18:38
  • 2
    I generally agree @Ovaryraptor a non-plug-in method is best to also include if you show the plug in answer. For what it's worth, the only must have plug in I know are the Astute plug ins for Illustrator. I can't recommend them highly enough.
    – Scott
    Commented Jan 22, 2018 at 18:44
  • @WELZ Your method seems to be altering the line shape as well. Commented Jan 22, 2018 at 21:44
  • @WELZ It's not the gif, your curves are shrinking in response to the corner rounding. He's looking to round the corners alone and not alter the curve of the object. Commented Jan 22, 2018 at 21:52
  • @Ovaryraptor I've overlayed them at 30% opacity i.sstatic.net/6UQhs.png and updated my answer with that as well. - like I said, it was a poor gif.
    – Welz
    Commented Jan 22, 2018 at 21:56

The easiest way would be to just plot out where you want the start and end of your rounding to be with guides.

Then using the add anchor point, +, and remove anchor point, -, tools.

enter image description here

Once you add each point, remove the corner point and using the anchor point tool, drag out the corner while holding down the Shift key to keep it inline with the top.

  • 1
    OP asked for a way to avoid doing this manually, IMHO this is about as manual as it gets.
    – Welz
    Commented Jan 23, 2018 at 15:50
  • Indeed it's a bit slow to do and I'm searching for a fast method :( ..but what I liked about this method is that you can prolong the size of the curve, so this is also helpful, thanks!
    – Soul Eater
    Commented Jan 29, 2018 at 2:04

If I did not have the VectorScribe plug in from AstuteGraphics.com (which I highly recommend)... I'd use circles and the Shape Builder Tool

  • Switch to outline mode (View > Outline)
  • Zoom in so you can see the paths well.
  • Draw a circle the diameter of your desired curve.
  • Align the circle to the edges of your existing shape.
  • Grab the Shape Builder Tool and merely drag across the corners.
  • Delete the circles.
  • Clean up as necessary.

enter image description here

You merely need to ensure the paths of the circle overlap the original object paths.

It's stuff like this which makes VectorScribe a "must have" in my opinion. It's not impossible to accomplish without the plug in, but 60 seconds manually or 3 seconds with the plug in. In addition the plug in is dynamic so I can alter the radius of the curve later if I need. There's no way to do that effectively without the plug in.

For what it's worth... I still work primarily in CS6 because I prefer it. I have CC but all Illustrator CC has done is copy the AstuteGrahics plug in functions and made them part of the native application, but they still aren't as good from Adobe as the plug ins are, even when using AICC. I use VectorScribe in both CS6 and CC.

  • I would've used Astute Graphics Subscribe (which is free) to make those circles perfectly aligned, see my post
    – Welz
    Commented Jan 23, 2018 at 12:45
  • Yup @WELZ but the point was without plug ins :)
    – Scott
    Commented Jan 23, 2018 at 15:40

Here's another method.

  1. Make the connector wider than you need.

  2. Then apply a thick stroke, and set the stroke to rounded corners.

enter image description here

  1. Object > Expand

  2. Object > Compound Path > Release

  3. Object > Ungroup.

  4. Select the outer shape and delete it, leaving the inner one.

enter image description here

  1. Apply new stroke and fill as required.

enter image description here

  • This is basically the same method as the offset method in I mentioned in teh last paragraph. (since stroke expansion is the same offset function)
    – joojaa
    Commented Jan 23, 2018 at 12:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.