Here is a link to a website that has a scale calculator. You can set the parameters to what ever size you want, then input the dimensions and it will re-calculate the dimensions into what ever scale you desire!!!
www.nhsouth.com/crafts/workbench/ss.htm
I use this all the time.
You can find a simpler version of a Scale Calculator in the ztrains.com website, but it does not have as many features. Here is the link to the ZTrains website
www.ztrains.com/pages/workshop/calculator/calculator.html
Save the page to your Internet Explorer Favorites and "Check" the view offline and you can use the calculator when not connected to the internet!!!
Hobo Tim