Favicons on popular sites and performance

What started out as an investigation to find out how many sites out there don’t have a favicon.ico file yet has turned into something  very interesting.

The importance of a favicon and the impact of it on performance has been discussed in various forums before, heck, it’s even listed in the first 14 rules of performance. So, how far have we come since 2007?

To find out more about favicons, I got the list of top 1000 sites from Alexa’s top 1,000,000 websites and wrote a small shell script to download the favicon.ico file from the webroot. That’s hostname/favicon.ico.

for i in `cat ../source/top-1m.csv | head -n 1000`
	url=`echo $i | cut  -d "," -f2`
	curl --dump-header ${url}_header.txt --location  \
	--retry 2 --user-agent \
	'Mozilla/5.0 (Windows; U; Windows NT 5.1; it; rv:' \
	-o ${url}_favicon.ico http://${url}/favicon.ico

Note: To keep things simple, I haven’t used favicons that are linked using the <link rel=”icon” …> and <link rel=”shortcut icon” …> notation.

Some interesting facts about the top 1000 favicons I downloaded:

  • 145 sites don’t have a favicon at the default location(i.e. hostname/favicon.ico)
  • 106 sites have a favicon greater than 5KB
  • Only 127 sites have a favicon smaller than 1KB
  • The biggest favicon file found was 187KB (http://naver.jp/favicon.ico)
  • The smallest favicon file found was 152 Bytes – facebook.com
  • Average size(top 1000-145) of a favicon file is 4.5 KB
  • Apple has a favicon of size 8.85 KB 

Favicons of some popular sites:

Washington Post

Wall Street Journal



Business Insider



Sky Sports

… the list goes on and on.

Things I learned:

  • What you see in Firefox/Safari/Chrome is not the complete favicon.ico file (There’s more to it – see images above)
  •  IE supports only .ico file format for favicons
  • So far, using Charles HTTP debugging proxy is the only way to see the full favicon image on a Mac. Let me know if any other viewer works for you. Preview on Mac doesn’t.

Next steps:

  • I’ll extend that script to download favicons from sites that follow the <link rel …> notation for favicons.
  • Not sure if you’ve seen my script carefully. I have saved the HTTP response header of the favicon.ico file for each domain. I’ll see if I can find anything interesting in that.
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  • Woh! I couldn’t believe it as well. Very nice post.

  • Shubhada

    Pravin, do you mean to say that favicon.ico file size does not directly impact the