For a couple of months now I've been creating favicons using Icon Composer (which comes with Xcode). It can save .ico files, and I know that sometimes Windows shows (or used to show) larger versions of the icon in some circumstances, so I thought I'd do it that way instead of just using a tiny .png.

Imagine my surprise when a Windows-using coworker tells me that he can't see any of the favicons I've created this way. No Windows browser seems to render them correctly, and only Firefox even attempts to render them at all.

So are .ico files produced by Icon Composer not supposed to be Windows-compatible? If not, is there any quick way to convert them into versions that are? If so, what might I be doing wrong?

UPDATE: Here is an example of a broken .ico file produced by Icon Composer. My coworkers are all on Windows 7, so it's not just a Windows XP issue.
an example of a broken .ico file

UPDATE 2: This happens with .ico files saved from both Icon Composer 2.1 (Xcode 3) and 2.2 (Xcode 4). In Firefox on Windows, display of these icons is corrupted; the icon is shifted to the right several pixels, and the right side is cut off and wraps around to the left side, as seen here:

  • What version of Windows is your co-worker using?
    – zpletan
    Sep 20, 2011 at 22:26
  • 1
    It should work...I wonder why it isn't.
    – daviesgeek
    Sep 21, 2011 at 2:19
  • Windows XP and older can have trouble opening ICOs with I think 256x256 (or greater size) compressed PNG images. If your ICOs have a size greater than or equal to 256x256, and your co-worker has Windows XP or older, then he will not be able to see the icons.
    – zpletan
    Sep 21, 2011 at 2:50
  • Alas, they're all on Windows 7. Sep 21, 2011 at 16:51
  • Then that's probably not it. :) Sorry.
    – zpletan
    Sep 21, 2011 at 17:17

3 Answers 3


Do you get the same issue if you try Hobiconer to export your icons? Superior to Icon Composer in every way, and free.

The commercial successor of Hobiconer called Icon Slate is $4.99 in the App Store, however Hobiconer is still out there for grabs (hence the link to Softpedia's mirrored file)

  • I picked up Icon Slate. It's a little fiddly, but its output works great. Thanks so much! Jan 21, 2012 at 4:19

What version of Icon Composer do you use?

I will upload the icon you listed after I made it a converted ico with Xcode 4's Icon Composer.


As noted 256x256 is what windows 7 uses for icons.

What exactly are you doing that required them to be in ico format?

If you are making web icons would it not be easier to use a different more generic format of an image such as a png or jpeg.

Edit: I tested my image made in the same format and in firefox on mac it decides to display the 16x16 instead of the 256x256 so maybe the browser is being selective on the sizes it presenting or it cannot process the way the ico file is built to determine the image size

Its hard for me to assist without really knowing the reason they need to be in ico format for view in web browsers

  • I have the same problem with both Icon Composer 2.1 (Xcode 3) and 2.2 (Xcode 4). The icon you uploaded is broken in Windows just as thoroughly as the one I uploaded. As I said in my original question, some versions of Windows use larger favicon sizes in certain circumstances (like when viewing the Properties window of an IE favorite). Firefox Windows displays yours incorrectly the same way it displays mine incorrectly. Sep 25, 2011 at 17:21
  • Are you needing to make icon files to display on the web or on Win7 screens for files or folders? Sep 25, 2011 at 19:02
  • 1
    Are you sure you've actually read my question? I'm creating favicons. Though the icons Icon Composer is creating don't work on Windows at all for either purpose. As I stated originally, I am fully aware that you can use .png files as favicons, but I would prefer not to, because Windows sometimes displays larger sizes of favicons, such as in the Properties window of IE Favorites, and also because my particular web development situation makes using .png icons more of a hassle. Sep 25, 2011 at 19:12
  • No need to insult me I hadn't seen your second update you added after I had previously read the question. I now know more of what your trying to do and will response if I find an answer to help you. Sep 25, 2011 at 20:13

My suggestion is to use GIMP instead of Icon Composer. I used to fiddle with Windows icons a fair bit, and it never messed up for me. My only problems with it (on Mac OS X) are:

  1. Much slower startup time compared to Icon Composer.
  2. Can't drag-and-drop (have to use File->Open [as Layers]).

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