For a 9" block, you'll need a 3 1/2" center piece and 4 3 1/2" x 6 1/2" pieces. At 9" blocks, I would do at the minimum a 6 x 7 block layout - 54" x 63" - to a maximum of 7 x 8 block layout - 63" x 72". It would depend on the person getting the quilt. So that would be 42 to 56 blocks, depending on which size.
(assuming fabric has a usable width of 40" - each measurement also gives about 1.5" for evening up and is rounded to the next 8th of a yard)
6 x 7 blocks / 54" x 63"
42 blocks
center:
1/2 yard - cut 4 strips 3 1/2" x w.o.f. Subcut each strip into 11 3 1/2" squares for a total of 44 squares
each color: 7/8 yard - cut 4 strips 6 1/2" x w.o.f. Subcut each strip into 11 rectangles 3 1/2" x 6 1/2" for a total of 44 rectangles of each color.
You will have 2 extra blocks.
6 x 8 blocks / 54" x 72" or 7 x 7 blocks / 63" x 63"
48 blocks / 49 blocks
center:
5/8 yard - cut 5 strips 3 1/2" x w.o.f. Subcut each strip into 11 3 1/2" squares for a total of 55 squares
each color: 1 yard - cut 5 strips 6 1/2" x w.o.f. Subcut each strip into 11 rectangles 3 1/2" x 6 1/2" for a total of 55 rectangles of each color.
You will have 7 or 6 extra blocks.
**** note, if your fabric is at least 42" usable and you are doing the 6x8 quilt, you can get away with the measurements for the 6x7 block quilt. You will need cuts and each cut will make 12 instead of 11 squares or rectangles, giving you 48 blocks total. The 7 x 7 block quilt requires 5 cuts even if the fabric is 42".
7 x 8 blocks / 63" x 72"
56 blocks
center:
5/8 yard - cut 6 strips 3 1/2" x w.o.f. Subcut each strip into 11 3 1/2" squares for a total of 66 squares
each color: 1 1/8 yard - cut 6 strips 6 1/2" x w.o.f. Subcut each strip into 11 rectangles 3 1/2" x 6 1/2" for a total of 66 rectangles of each color.
You will have 10 extra blocks.
**** note, if your fabric is at least 42" usable, you can get away with the measurements for the 6x8 or 7x7 block quilt. You will need 5 cuts and each cut will make 12 instead of 11 squares or rectangles, giving you 60 blocks total.