seasaw2mch

I just did one that was 54X78 but I used strips that were cut 30" long so the rows come out like I wanted.

Here is how I figured out what size stripes to cut.
The length is 78" so divide that by 2" (finished size, cut size 2 1/2") you need 39 rows to make the length. This is an odd number so I dropped the last row and only did 38 rows. I added a 1" border to make up the 78" that I wanted.
Now the width I used was 54 - 2" for border= 52" so multiply that by 38 rows and you get 1,976 inches, this is how many inches you need to make the quilt.

so the length divided by width of strips (adjust for odd numbers), multiplied by the width of the quilt (minus any adjustments) equals the total length of fabric strips you need.

Next thing you need to do is divide 1,976 by the number of fabrics that you want in you quilt, that will give you an idea of how long the stripes should be. If the needed strip length is longer than your fabric then you will need 2 pieces of each fabric and I would divide the length of the needed strips by 2 so your strips would be equal in length but that is up to you.

For myself, I didn't want to use any fabric more then once and I didn't want the strips 40" long in the quilt either so I ended up using 69 fabrics cut 30" long (finished about 28 1/2") plus 1 strips about 12 long ".

I hope all this makes sense but it's all in the math.