I don't know if this will help, but this is a very cool enlargement chart for blocks.
http://www.thequiltedsnail.com/scale.html
I drew a 7 inch block out in Excel. If I wanted to turn it into a 14" block, the block became 4 times bigger, because it is double as wide and double as long, thereby having to add 3 more 7 inch blocks to it. To me, this means, I would have to buy 4 times as much material as the pattern called for. Not having tried or verified this, I would definitely rely on the quilters here who know what they are doing.
This board makes me think and question what do I really know about quilting? I always learn something new.