Recent mock-ups for the home tab, new tab, awesome bar and full screen mode all call for larger site icons. Although I wrote some code to expand a 16x16 favicon using the icon’s dominant color, a larger icon specified by the site would really be ideal.

The HTML5 spec for link type “icon” describes a sizes attribute, which enables web authors to specify multiple icon sizes. I was curious if anyone was already using this attribute, so I wrote a python script to inspect the 1000 most-visited websites, as reported by Google. Unfortunately, I found that only one website is using this sizes attribute. However, that’s not too surprising, considering this is a new spec that doesn’t seem to do much for websites right now.

I was also curious about how many websites specify link type “apple-touch-icon”, which is a way to specify a larger icon for iOS app shortcuts. I found that 81 of these top 1000 websites include these tags. However, I realized that smart websites would probably only provide this icon for users on iOS devices, so I decided to modify my script to spoof an iPhone user agent header. When I made this change, I found that 225 of these top 1000 websites included an apple-touch-icon.

Based on this data, I’d say that if we started including larger icons in the Firefox UI, icons that web authors can provide according to the HTML5 spec, plenty of websites would be willing to include larger icons in their link tags.

A handful of websites, such as and, are already including multiple icon sizes in their favicon.ico files, even though they are not communicating this with a sizes attribute. Unfortunately, even if they included a sizes attribute, we don’t currently have platform support for getting multiple icon sizes out of ICO files. However, work is being done there, so hopefully we will be able to use these larger icons in the near future.

The data from my investigation, including a JSON mapping of site URLs to icon URLs, is available here: