I found a very interesting web site that calculates the Return on Security Investment by Dejan Kosutic blog.
You can use the calculator using this link: http://www.iso27001standard.com/en/rosi/return-on-security-investment?utm_source=linkedin&utm_medium=dk&utm_campaign=tools.
And if you need more information about the tool you can check on his blog down here:
There http://blog.iso27001standard.com/2011/06/13/is-it-possible-to-calculate-the-return-on-security-investment-rosi/
