First, you take the standard size for a Queen Sized Quilt.. we really don't have enough info.. what are the other blocks, and are you putting on a border?. If no border take 12" and divide into each dimension of the standard Queen sized quilt 96" x 98".. so it would actually come out to 8 blocks by 8 blocks. or a total of 64 blocks.. which will make it 2" short. so half of those blocks would be 32. so if those 32 blocks are 9 patch you need to find the yardage for those blocks.. as they are 9 patch, if they are all identical you will have more pieces of one color than the other. Lets assume you are going to alternate the 9 patches. That way the yardages will come out even. Each piece within that block will be 4" square. Keep that number in your head. ok. 9 patches times 32 blocks would be 288 total patches. Half for each color so that's 144 of each color. each patch will be 4" plus 1/2" for standard seam allowance. standard fabric is 44" wide so you can get 9 blocks across the width. 144patches divided by 9 would be 16 rows. 16 x 4.5 would be 72" which is 2 yards. so looks like to me you would need 2 yards of each color.....that is only for the 9 patch blocks....and does not allow ANY leeway for error... I always get a bit more and would probably buy 2.5 yards of each color ...besides that's how stashes grow.