To continue with math
Say you want to do a 12" 9 patch for a queen quilt.
Quilt is 96"x108" There will be a total of 72 blocks in the quilt. 96" divided by 12" and 108" divided by 12 = 72
Each 9 patch block contains 9 squares finished at 4". So cut will be 4.5"
4.5"x4.5" = 20.25 square inches.
20.25 x 9 = 182.25 square inches each block
182.25 x 72 blocks is 13122 total square inches.
1512 square inches in a yd of fabric
13122 divided by 1512 = 8.67 total yds.
Now, assume you want to use two colors in your blocks then the 8.67 divided by 2 is 4.33 or little over 4 and 1/3 yd of each color. But add a half yard for miscuts.
Calculating for binding.
Measure around quilt = 408" width of fabric is 42"
Divide 42 into 408 = 9.7 strips (make it 10 strips)
If each strip is cut 2.5" then 2.5 x 10 is 25 inches of fabric for the binding.
I woke up and couldn't sleep