I am wondering if there is a way to make GIMP (2.8 on Mac) allow me to make a rectangle with rounded corners - the radius being over 100 px. This seems to be the current limit.

This would greatly help me make great looking iOS app icons.


The functionality is buried in GIMP in a function called gimp-image-select-round-rectangle. See the bug report.

I have exposed gimp-image-select-round-rectangle's ability to create rounded rectangles with a radius > 100 (actually up to 262144 pixels now) to the UI with a script-fu script, select_round_rectangle.scm The script also exposes the ability to create rounded rectangles with different x & y radii.

enter image description here


Having read and responded to the above, I went hunting and have found that under the Filters menu at Filter->Decor->Round Corners... we have the ability to clip the image as desired, setting the radius as desired.

I note that you seem to be restricted to RGB, and a single layer image to be able to use this filter. Even then it doesn't always seem to be enabled. In any case it works for me.


The radius in the Select -> Rounded Rectangle dialog in Gimp 2.8 is actually a percentage. It wouldn't make sense for it to go over 100 percent.

At least, this is the case for me on Gimp 2.8.2/Windows.

Personally, I prefer a little bit more control so I do this kind of stuff in Inkscape, an SVG-based vector editor. I can still then export to GIMP.

Edit: So it turns out there are two different places where you can create a rounded rectangle.

  1. Using the select tool on the toolbar, before making the selection, check "Rounded Rectangle" in the tool options. Here you can make a radius only up to 100 pixels.

  2. By making a normal rectangular selection, and then going to the "Select" menu, then "Rounded Rectangle". This allows you to round the rectangle you've already selected by a certain percentage, where 100% is the maximum amount of rounding possible on that selection (50% of the smaller dimention of the selected rectangle).

  • So... There's a cap on how rounded my rectangles can be? I'm trying to get an iOS app icon with rounded corners that match the ones forced on be the system.
    – Undo
    Jan 9 '13 at 14:37
  • No, no cap. 100% means that it's as rounded as it can possibly be. The percent sign means that it isn't measured in pixels, percentage is a measurement where "100%" is the maximum, meaning the diameter is the same as the smaller dimension of your rectange. 100% on a square would turn it into a circle, for instance. You can't get any more rounded than it. Perhaps I've misunderstood your question, or what you want to do - if so could you add an example of what you want to achieve to your question? Jan 11 '13 at 0:03
  • I can't speak for the Windows version, but on the Mac that field is NOT a percentage. Hovering over the field reveals a tooltip stating "Radius of rounding in pixels". I too would like to setup a radius > 100 pixels for the purposes of creating an iOS app icon.
    – PKCLsoft
    Jun 2 '13 at 0:27
  • I have a hard time believing they would implement it differently for the Mac. Do you have a screenshot? Here's the relevant page of the documentation saying it's a percentage: docs.gimp.org/en/script-fu-selection-rounded-rectangle.html Jun 2 '13 at 4:03
  • Sure, here's a screenshot at: link
    – PKCLsoft
    Jun 2 '13 at 13:09

As it's an iOS icon I assume it's square. A radius of 100% would give a radius of half the width and height of your image (making a perfect circle). Apple's icon radius is a value of 10/57 (0.1754 or 17.5%) as Gimp's percentage works on half the icon size we need to double that value to 35%.

In brief: Goto Select menu > Rounded Rectangle... > Enter a value of 35 > Ok

This is in Gimp 2.8.10 on Mac.

Note: If you're wanting the pixel size of the radius it will be 10*size/57 where size is the size of the icon.

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    Jun 3 '15 at 12:34

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