I will be doing a 3 tier square wedding cake (6, 8, 10) - each layer will be 2 cakes, torted once (ie. 2 (6 in.) each torted once). Using 3" pans. I want to order pre-colored SI fondant - about how much do you think I'll need?

Thanks in advance!

http://www.wilton.com/decorating/fondant/fondant-coverage-chart.cfm