Don't know if this helps...but if this is a log cabin block based quilt.... example...if all the log cabin squares are the same size - and it takes 1/2 yard of 10 different fabrics to make 20 log cabin blocks - it would take 3/4 yard each to make 30 - and a full yard of each to make 40. How much fabric is required for the original squares?? Then how many additional squares do you need to make the size you want?